diff --git a/beacon-chain/blockchain/core.go b/beacon-chain/blockchain/core.go
index b5e52d70e6..f9e15642a9 100644
--- a/beacon-chain/blockchain/core.go
+++ b/beacon-chain/blockchain/core.go
@@ -300,7 +300,7 @@ func (b *BeaconChain) getAttestation(hash [32]byte) (*types.Attestation, error)
 		return nil, err
 	}
 
-	attestation := &pb.AttestationRecord{}
+	attestation := &pb.AggregatedAttestation{}
 
 	err = proto.Unmarshal(enc, attestation)
 
diff --git a/beacon-chain/blockchain/core_test.go b/beacon-chain/blockchain/core_test.go
index feb5a120d1..58ec01f5bd 100644
--- a/beacon-chain/blockchain/core_test.go
+++ b/beacon-chain/blockchain/core_test.go
@@ -151,7 +151,7 @@ func TestSetActiveState(t *testing.T) {
 	defer db.Close()
 
 	data := &pb.ActiveState{
-		PendingAttestations: []*pb.AttestationRecord{
+		PendingAttestations: []*pb.AggregatedAttestation{
 			{Slot: 0, ShardBlockHash: []byte{1}}, {Slot: 1, ShardBlockHash: []byte{2}},
 		},
 		RecentBlockHashes: [][]byte{
@@ -370,7 +370,7 @@ func TestSaveAndRemoveAttestations(t *testing.T) {
 	b, db := startInMemoryBeaconChain(t)
 	defer db.Close()
 
-	attestation := types.NewAttestation(&pb.AttestationRecord{
+	attestation := types.NewAttestation(&pb.AggregatedAttestation{
 		Slot:             1,
 		ShardId:          1,
 		AttesterBitfield: []byte{'A'},
@@ -390,7 +390,7 @@ func TestSaveAndRemoveAttestations(t *testing.T) {
 	}
 
 	// Adding a different attestation with the same key
-	newAttestation := types.NewAttestation(&pb.AttestationRecord{
+	newAttestation := types.NewAttestation(&pb.AggregatedAttestation{
 		Slot:             2,
 		ShardId:          2,
 		AttesterBitfield: []byte{'B'},
@@ -440,7 +440,7 @@ func TestSaveAndRemoveAttestationHashList(t *testing.T) {
 		t.Error(err)
 	}
 
-	attestation := types.NewAttestation(&pb.AttestationRecord{
+	attestation := types.NewAttestation(&pb.AggregatedAttestation{
 		Slot:             1,
 		ShardId:          1,
 		AttesterBitfield: []byte{'A'},
diff --git a/beacon-chain/blockchain/service.go b/beacon-chain/blockchain/service.go
index 39dcd24198..8fc93d2eaf 100644
--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -127,6 +127,15 @@ func (c *ChainService) ContainsBlock(h [32]byte) (bool, error) {
 	return c.chain.hasBlock(h)
 }
 
+// GetBlockSlotNumber returns the slot number of a block.
+func (c *ChainService) GetBlockSlotNumber(h [32]byte) (uint64, error) {
+	block, err := c.chain.getBlock(h)
+	if err != nil {
+		return 0, fmt.Errorf("could not get block from DB: %v", err)
+	}
+	return block.SlotNumber(), nil
+}
+
 // CurrentCrystallizedState of the canonical chain.
 func (c *ChainService) CurrentCrystallizedState() *types.CrystallizedState {
 	return c.chain.CrystallizedState()
@@ -228,14 +237,18 @@ func (c *ChainService) blockProcessing(done <-chan struct{}) {
 		case <-done:
 			log.Debug("Chain service context closed, exiting goroutine")
 			return
-			// Listen for a newly received incoming block from the sync service.
+		// Listen for a newly received incoming attestation from the sync service.
 		case attestation := <-c.incomingAttestationChan:
 			h, err := attestation.Hash()
 			if err != nil {
 				log.Debugf("Could not hash incoming attestation: %v", err)
 			}
-			log.Info("Relaying attestation 0x%v to p2p service", h)
+			if err := c.chain.saveAttestation(attestation); err != nil {
+				log.Errorf("Could not save attestation: %v", err)
+				continue
+			}
 
+			log.Infof("Relaying attestation 0x%x to subscriber", h)
 			// TODO: Send attestation to P2P and broadcast attestation to rest of the peers.
 
 		// Listen for a newly received incoming block from the sync service.
@@ -260,7 +273,7 @@ func (c *ChainService) blockProcessing(done <-chan struct{}) {
 				log.Errorf("Could not check existence of parent: %v", err)
 				continue
 			}
-			// Get parent slot number.
+
 			parentBlock, err := c.chain.getBlock(block.ParentHash())
 			if err != nil {
 				log.Errorf("Could not get parent block: %v", err)
@@ -271,7 +284,7 @@ func (c *ChainService) blockProcessing(done <-chan struct{}) {
 				continue
 			}
 
-			// If a candidate block exists and it is a lower slot, run theh fork choice rule.
+			// If a candidate block exists and it is a lower slot, run the fork choice rule.
 			if c.candidateBlock != nilBlock && block.SlotNumber() > c.candidateBlock.SlotNumber() {
 				c.updateHead()
 			}
diff --git a/beacon-chain/blockchain/service_test.go b/beacon-chain/blockchain/service_test.go
index df2f0064fb..e400c6d2aa 100644
--- a/beacon-chain/blockchain/service_test.go
+++ b/beacon-chain/blockchain/service_test.go
@@ -264,9 +264,9 @@ func TestRunningChainService(t *testing.T) {
 		CrystallizedStateHash: crystallizedStateHash[:],
 		ParentHash:            parentHash[:],
 		PowChainRef:           []byte("a"),
-		Attestations: []*pb.AttestationRecord{{
+		Attestations: []*pb.AggregatedAttestation{{
 			Slot:             0,
-			AttesterBitfield: []byte{'A', 'B'},
+			AttesterBitfield: []byte{128, 0},
 			ShardId:          0,
 		}},
 	})
@@ -284,6 +284,21 @@ func TestRunningChainService(t *testing.T) {
 	chainService.cancel()
 	exitRoutine <- true
 
+	hash, err := block.Hash()
+	if err != nil {
+		t.Fatal("Can not hash the block")
+	}
+	slot, err := chainService.GetBlockSlotNumber(hash)
+	if err != nil {
+		t.Fatal("Can not get block slot number")
+	}
+	if slot != block.SlotNumber() {
+		t.Errorf("Block slot number mismatched, wanted 1, got slot %d", block.SlotNumber())
+	}
+	if _, err := chainService.GetBlockSlotNumber([32]byte{}); err == nil {
+		t.Fatal("Get block slot number should have failed with nil hash")
+	}
+
 	testutil.AssertLogsContain(t, hook, "Finished processing state for candidate block")
 }
 
@@ -345,69 +360,6 @@ func TestUpdateHead(t *testing.T) {
 	}
 }
 
-func TestProcessingBlockWithAttestations(t *testing.T) {
-	ctx := context.Background()
-	config := &database.DBConfig{DataDir: "", Name: "", InMemory: true}
-	db, err := database.NewDB(config)
-	if err != nil {
-		t.Fatalf("could not setup beaconDB: %v", err)
-
-	}
-	endpoint := "ws://127.0.0.1"
-	client := &mockClient{}
-	web3Service, err := powchain.NewWeb3Service(ctx, &powchain.Web3ServiceConfig{Endpoint: endpoint, Pubkey: "", VrcAddr: common.Address{}}, client, client, client)
-	if err != nil {
-		t.Fatalf("unable to set up web3 service: %v", err)
-	}
-	beaconChain, err := NewBeaconChain(db.DB())
-	if err != nil {
-		t.Fatalf("could not register blockchain service: %v", err)
-	}
-
-	active := beaconChain.ActiveState()
-	activeHash, _ := active.Hash()
-
-	crystallized := beaconChain.CrystallizedState()
-	crystallizedHash, _ := crystallized.Hash()
-
-	cfg := &Config{
-		BeaconBlockBuf: 0,
-		BeaconDB:       db.DB(),
-		Chain:          beaconChain,
-		Web3Service:    web3Service,
-	}
-
-	chainService, _ := NewChainService(ctx, cfg)
-
-	exitRoutine := make(chan bool)
-	go func() {
-		chainService.blockProcessing(chainService.ctx.Done())
-		<-exitRoutine
-	}()
-
-	parentBlock := types.NewBlock(nil)
-	if err := chainService.SaveBlock(parentBlock); err != nil {
-		t.Fatal(err)
-	}
-	parentHash, _ := parentBlock.Hash()
-
-	block := types.NewBlock(&pb.BeaconBlock{
-		SlotNumber:            2,
-		ActiveStateHash:       activeHash[:],
-		CrystallizedStateHash: crystallizedHash[:],
-		ParentHash:            parentHash[:],
-		PowChainRef:           []byte("a"),
-		Attestations: []*pb.AttestationRecord{
-			{Slot: 0, ShardId: 0, AttesterBitfield: []byte{'0'}},
-		},
-	})
-
-	chainService.incomingBlockChan <- block
-	chainService.cancel()
-	exitRoutine <- true
-
-}
-
 func TestProcessingBlocks(t *testing.T) {
 	ctx := context.Background()
 	config := &database.DBConfig{DataDir: "", Name: "", InMemory: true}
@@ -467,9 +419,9 @@ func TestProcessingBlocks(t *testing.T) {
 		SlotNumber:            4,
 		ActiveStateHash:       activeStateHash[:],
 		CrystallizedStateHash: crystallizedStateHash[:],
-		Attestations: []*pb.AttestationRecord{{
+		Attestations: []*pb.AggregatedAttestation{{
 			Slot:             0,
-			AttesterBitfield: []byte{0, 0},
+			AttesterBitfield: []byte{16, 0},
 			ShardId:          0,
 		}},
 	})
@@ -482,9 +434,9 @@ func TestProcessingBlocks(t *testing.T) {
 	block2 := types.NewBlock(&pb.BeaconBlock{
 		ParentHash: block1Hash[:],
 		SlotNumber: 5,
-		Attestations: []*pb.AttestationRecord{
-			{Slot: 0, AttesterBitfield: []byte{0, 0}, ShardId: 0},
-			{Slot: 1, AttesterBitfield: []byte{0, 0}, ShardId: 0},
+		Attestations: []*pb.AggregatedAttestation{
+			{Slot: 0, AttesterBitfield: []byte{8, 0}, ShardId: 0},
+			{Slot: 1, AttesterBitfield: []byte{8, 0}, ShardId: 0},
 		}})
 	block2Hash, err := block2.Hash()
 	if err != nil {
@@ -495,10 +447,10 @@ func TestProcessingBlocks(t *testing.T) {
 	block3 := types.NewBlock(&pb.BeaconBlock{
 		ParentHash: block2Hash[:],
 		SlotNumber: 6,
-		Attestations: []*pb.AttestationRecord{
-			{Slot: 0, AttesterBitfield: []byte{0, 0}, ShardId: 0},
-			{Slot: 1, AttesterBitfield: []byte{0, 0}, ShardId: 0},
-			{Slot: 2, AttesterBitfield: []byte{0, 0}, ShardId: 0},
+		Attestations: []*pb.AggregatedAttestation{
+			{Slot: 0, AttesterBitfield: []byte{4, 0}, ShardId: 0},
+			{Slot: 1, AttesterBitfield: []byte{4, 0}, ShardId: 0},
+			{Slot: 2, AttesterBitfield: []byte{4, 0}, ShardId: 0},
 		}})
 
 	chainService.incomingBlockChan <- block1
@@ -573,7 +525,7 @@ func TestProcessAttestationBadBlock(t *testing.T) {
 		SlotNumber:            1,
 		ActiveStateHash:       activeStateHash[:],
 		CrystallizedStateHash: crystallizedStateHash[:],
-		Attestations: []*pb.AttestationRecord{{
+		Attestations: []*pb.AggregatedAttestation{{
 			Slot:             10,
 			AttesterBitfield: []byte{},
 			ShardId:          0,
@@ -636,9 +588,9 @@ func TestEnterCycleTransition(t *testing.T) {
 		SlotNumber:            64,
 		ActiveStateHash:       activeStateHash[:],
 		CrystallizedStateHash: crystallizedStateHash[:],
-		Attestations: []*pb.AttestationRecord{{
+		Attestations: []*pb.AggregatedAttestation{{
 			Slot:             0,
-			AttesterBitfield: []byte{0, 0},
+			AttesterBitfield: []byte{128, 0},
 			ShardId:          0,
 		}},
 	})
@@ -708,6 +660,7 @@ func TestEnterDynastyTransition(t *testing.T) {
 			LastFinalizedSlot:          2,
 			ShardAndCommitteesForSlots: shardCommitteeForSlots,
 			Validators:                 validators,
+			LastStateRecalc:            150,
 			CrosslinkRecords: []*pb.CrosslinkRecord{
 				{Slot: 2},
 				{Slot: 2},
@@ -724,7 +677,7 @@ func TestEnterDynastyTransition(t *testing.T) {
 	active := types.NewActiveState(
 		&pb.ActiveState{
 			RecentBlockHashes: recentBlockhashes,
-			PendingAttestations: []*pb.AttestationRecord{
+			PendingAttestations: []*pb.AggregatedAttestation{
 				{Slot: 100, AttesterBitfield: []byte{0}},
 				{Slot: 101, AttesterBitfield: []byte{0}},
 				{Slot: 102, AttesterBitfield: []byte{0}},
@@ -758,9 +711,9 @@ func TestEnterDynastyTransition(t *testing.T) {
 		SlotNumber:            params.MinDynastyLength + 1,
 		ActiveStateHash:       activeStateHash[:],
 		CrystallizedStateHash: crystallizedStateHash[:],
-		Attestations: []*pb.AttestationRecord{{
+		Attestations: []*pb.AggregatedAttestation{{
 			Slot:             200,
-			AttesterBitfield: []byte{0},
+			AttesterBitfield: []byte{32},
 			ShardId:          0,
 		}},
 	})
@@ -778,3 +731,52 @@ func TestEnterDynastyTransition(t *testing.T) {
 
 	testutil.AssertLogsContain(t, hook, "Entering dynasty transition")
 }
+
+func TestIncomingAttestation(t *testing.T) {
+	hook := logTest.NewGlobal()
+	ctx := context.Background()
+	config := &database.DBConfig{DataDir: "", Name: "", InMemory: true}
+	db, err := database.NewDB(config)
+	if err != nil {
+		t.Fatalf("could not setup beaconDB: %v", err)
+	}
+
+	endpoint := "ws://127.0.0.1"
+	client := &mockClient{}
+	web3Service, err := powchain.NewWeb3Service(ctx, &powchain.Web3ServiceConfig{Endpoint: endpoint, Pubkey: "", VrcAddr: common.Address{}}, client, client, client)
+	if err != nil {
+		t.Fatalf("unable to set up web3 service: %v", err)
+	}
+	beaconChain, err := NewBeaconChain(db.DB())
+	if err != nil {
+		t.Fatalf("could not register blockchain service: %v", err)
+	}
+
+	cfg := &Config{
+		BeaconBlockBuf: 0,
+		BeaconDB:       db.DB(),
+		Chain:          beaconChain,
+		Web3Service:    web3Service,
+	}
+
+	chainService, _ := NewChainService(ctx, cfg)
+
+	exitRoutine := make(chan bool)
+	go func() {
+		chainService.blockProcessing(chainService.ctx.Done())
+		<-exitRoutine
+	}()
+
+	attestation := types.NewAttestation(
+		&pb.AggregatedAttestation{
+			Slot:           1,
+			ShardId:        1,
+			ShardBlockHash: []byte{'A'},
+		})
+
+	chainService.incomingAttestationChan <- attestation
+	chainService.cancel()
+	exitRoutine <- true
+
+	testutil.AssertLogsContain(t, hook, "Relaying attestation")
+}
diff --git a/beacon-chain/casper/incentives.go b/beacon-chain/casper/incentives.go
index e613f3499e..b1726f5a13 100644
--- a/beacon-chain/casper/incentives.go
+++ b/beacon-chain/casper/incentives.go
@@ -11,7 +11,7 @@ var log = logrus.WithField("prefix", "casper")
 
 // CalculateRewards adjusts validators balances by applying rewards or penalties
 // based on FFG incentive structure.
-func CalculateRewards(attestations []*pb.AttestationRecord, validators []*pb.ValidatorRecord, dynasty uint64, totalDeposit uint64) ([]*pb.ValidatorRecord, error) {
+func CalculateRewards(attestations []*pb.AggregatedAttestation, validators []*pb.ValidatorRecord, dynasty uint64, totalDeposit uint64) ([]*pb.ValidatorRecord, error) {
 	activeValidators := ActiveValidatorIndices(validators, dynasty)
 	attesterDeposits := GetAttestersTotalDeposit(attestations)
 
diff --git a/beacon-chain/casper/incentives_test.go b/beacon-chain/casper/incentives_test.go
index b494b6f0f7..f23392ee9f 100644
--- a/beacon-chain/casper/incentives_test.go
+++ b/beacon-chain/casper/incentives_test.go
@@ -22,7 +22,7 @@ func TestComputeValidatorRewardsAndPenalties(t *testing.T) {
 	}
 
 	// Binary representation of bitfield: 11001000 10010100 10010010 10110011 00110001
-	testAttesterBitfield := []*pb.AttestationRecord{{AttesterBitfield: []byte{200, 148, 146, 179, 49}}}
+	testAttesterBitfield := []*pb.AggregatedAttestation{{AttesterBitfield: []byte{200, 148, 146, 179, 49}}}
 	rewardedValidators, err := CalculateRewards(
 		testAttesterBitfield,
 		data.Validators,
diff --git a/beacon-chain/casper/validator.go b/beacon-chain/casper/validator.go
index c70d64e56a..c05927b8f1 100644
--- a/beacon-chain/casper/validator.go
+++ b/beacon-chain/casper/validator.go
@@ -92,12 +92,10 @@ func SampleAttestersAndProposers(seed common.Hash, validators []*pb.ValidatorRec
 }
 
 // GetAttestersTotalDeposit from the pending attestations.
-func GetAttestersTotalDeposit(attestations []*pb.AttestationRecord) uint64 {
+func GetAttestersTotalDeposit(attestations []*pb.AggregatedAttestation) uint64 {
 	var numOfBits int
 	for _, attestation := range attestations {
-		for _, byte := range attestation.AttesterBitfield {
-			numOfBits += int(utils.BitSetCount(byte))
-		}
+		numOfBits += int(utils.BitSetCount(attestation.AttesterBitfield))
 	}
 	// Assume there's no slashing condition, the following logic will change later phase.
 	return uint64(numOfBits) * params.DefaultBalance
@@ -113,7 +111,7 @@ func GetShardAndCommitteesForSlot(shardCommittees []*pb.ShardAndCommitteeArray,
 
 // AreAttesterBitfieldsValid validates that the length of the attester bitfield matches the attester indices
 // defined in the Crystallized State.
-func AreAttesterBitfieldsValid(attestation *pb.AttestationRecord, attesterIndices []uint32) bool {
+func AreAttesterBitfieldsValid(attestation *pb.AggregatedAttestation, attesterIndices []uint32) bool {
 	// Validate attester bit field has the correct length.
 	if utils.BitLength(len(attesterIndices)) != len(attestation.AttesterBitfield) {
 		log.Debugf("attestation has incorrect bitfield length. Found %v, expected %v",
@@ -137,3 +135,24 @@ func AreAttesterBitfieldsValid(attestation *pb.AttestationRecord, attesterIndice
 
 	return true
 }
+
+// GetProposerIndexAndShard returns the index and the shardID of a proposer from a given slot.
+func GetProposerIndexAndShard(shardCommittees []*pb.ShardAndCommitteeArray, lcs uint64, slot uint64) (uint64, uint64, error) {
+	if lcs < params.CycleLength {
+		lcs = 0
+	} else {
+		lcs = lcs - params.CycleLength
+	}
+
+	slotCommittees, err := GetShardAndCommitteesForSlot(
+		shardCommittees,
+		lcs,
+		slot)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	proposerShardID := slotCommittees.ArrayShardAndCommittee[0].ShardId
+	proposerIndex := slot % uint64(len(slotCommittees.ArrayShardAndCommittee[0].Committee))
+	return proposerShardID, proposerIndex, nil
+}
diff --git a/beacon-chain/casper/validator_test.go b/beacon-chain/casper/validator_test.go
index 4a768b41b0..3a0a7be19b 100644
--- a/beacon-chain/casper/validator_test.go
+++ b/beacon-chain/casper/validator_test.go
@@ -67,7 +67,7 @@ func TestRotateValidatorSet(t *testing.T) {
 
 func TestHasVoted(t *testing.T) {
 	// Setting bit field to 11111111.
-	pendingAttestation := &pb.AttestationRecord{
+	pendingAttestation := &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{255},
 	}
 
@@ -79,7 +79,7 @@ func TestHasVoted(t *testing.T) {
 	}
 
 	// Setting bit field to 01010101.
-	pendingAttestation = &pb.AttestationRecord{
+	pendingAttestation = &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{85},
 	}
 
@@ -141,7 +141,7 @@ func TestValidatorIndices(t *testing.T) {
 }
 
 func TestAreAttesterBitfieldsValid(t *testing.T) {
-	attestation := &pb.AttestationRecord{
+	attestation := &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{'F'},
 	}
 
@@ -154,7 +154,7 @@ func TestAreAttesterBitfieldsValid(t *testing.T) {
 }
 
 func TestAreAttesterBitfieldsValidFalse(t *testing.T) {
-	attestation := &pb.AttestationRecord{
+	attestation := &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{'F', 'F'},
 	}
 
@@ -167,7 +167,7 @@ func TestAreAttesterBitfieldsValidFalse(t *testing.T) {
 }
 
 func TestAreAttesterBitfieldsValidZerofill(t *testing.T) {
-	attestation := &pb.AttestationRecord{
+	attestation := &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{'F'},
 	}
 
@@ -180,7 +180,7 @@ func TestAreAttesterBitfieldsValidZerofill(t *testing.T) {
 }
 
 func TestAreAttesterBitfieldsValidNoZerofill(t *testing.T) {
-	attestation := &pb.AttestationRecord{
+	attestation := &pb.AggregatedAttestation{
 		AttesterBitfield: []byte{'E'},
 	}
 
@@ -191,3 +191,24 @@ func TestAreAttesterBitfieldsValidNoZerofill(t *testing.T) {
 		t.Fatalf("expected validation to fail for bitfield %v and indices %v", attestation, indices)
 	}
 }
+
+func TestGetProposerIndexAndShard(t *testing.T) {
+	shardCommittees := []*pb.ShardAndCommitteeArray{
+		{ArrayShardAndCommittee: []*pb.ShardAndCommittee{
+			{ShardId: 99, Committee: []uint32{0, 1, 2, 3, 4}},
+		}},
+	}
+	if _, _, err := GetProposerIndexAndShard(shardCommittees, 100, 0); err == nil {
+		t.Error("GetProposerIndexAndShard should have failed with invalid lcs")
+	}
+	shardID, index, err := GetProposerIndexAndShard(shardCommittees, 0, 0)
+	if err != nil {
+		t.Fatalf("GetProposerIndexAndShard failed with %v", err)
+	}
+	if shardID != 99 {
+		t.Errorf("Invalid shard ID. Wanted 99, got %d", shardID)
+	}
+	if index != 0 {
+		t.Errorf("Invalid proposer index. Wanted 0, got %d", index)
+	}
+}
diff --git a/beacon-chain/rpc/service_test.go b/beacon-chain/rpc/service_test.go
index 38837444a3..3a277afebe 100644
--- a/beacon-chain/rpc/service_test.go
+++ b/beacon-chain/rpc/service_test.go
@@ -254,7 +254,7 @@ func TestAttestHead(t *testing.T) {
 		ChainService: mockChain,
 	})
 	req := &pb.AttestRequest{
-		Attestation: &pbp2p.AttestationRecord{
+		Attestation: &pbp2p.AggregatedAttestation{
 			Slot:           999,
 			ShardId:        1,
 			ShardBlockHash: []byte{'a'},
diff --git a/beacon-chain/simulator/service.go b/beacon-chain/simulator/service.go
index 81b590cfe9..db04e48eca 100644
--- a/beacon-chain/simulator/service.go
+++ b/beacon-chain/simulator/service.go
@@ -214,7 +214,7 @@ func (sim *Simulator) run(delayChan <-chan time.Time, done <-chan struct{}) {
 			}
 			log.Debugf("Responding to full block request for hash: 0x%x", h)
 			// Sends the full block body to the requester.
-			res := &pb.BeaconBlockResponse{Block: block.Proto()}
+			res := &pb.BeaconBlockResponse{Block: block.Proto(), Attestation: nil}
 			sim.p2p.Send(res, msg.Peer)
 		}
 	}
diff --git a/beacon-chain/sync/BUILD.bazel b/beacon-chain/sync/BUILD.bazel
index 300318d61e..2e20296c3e 100644
--- a/beacon-chain/sync/BUILD.bazel
+++ b/beacon-chain/sync/BUILD.bazel
@@ -6,6 +6,7 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/sync",
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
+        "//beacon-chain/casper:go_default_library",
         "//beacon-chain/types:go_default_library",
         "//proto/beacon/p2p/v1:go_default_library",
         "//shared/p2p:go_default_library",
diff --git a/beacon-chain/sync/service.go b/beacon-chain/sync/service.go
index 50f4fc6bfa..3162d18445 100644
--- a/beacon-chain/sync/service.go
+++ b/beacon-chain/sync/service.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/event"
+	"github.com/prysmaticlabs/prysm/beacon-chain/casper"
 	"github.com/prysmaticlabs/prysm/beacon-chain/types"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	"github.com/prysmaticlabs/prysm/shared/p2p"
@@ -18,8 +19,11 @@ type chainService interface {
 	ContainsBlock(h [32]byte) (bool, error)
 	HasStoredState() (bool, error)
 	IncomingBlockFeed() *event.Feed
+	IncomingAttestationFeed() *event.Feed
 	CheckForCanonicalBlockBySlot(slotnumber uint64) (bool, error)
 	GetCanonicalBlockBySlotNumber(slotnumber uint64) (*types.Block, error)
+	GetBlockSlotNumber(h [32]byte) (uint64, error)
+	CurrentCrystallizedState() *types.CrystallizedState
 }
 
 // Service is the gateway and the bridge between the p2p network and the local beacon chain.
@@ -158,12 +162,14 @@ func (ss *Service) run() {
 				log.Error("Received malformed beacon block p2p message")
 				continue
 			}
+
 			block := types.NewBlock(response.Block)
-			h, err := block.Hash()
+			blockHash, err := block.Hash()
 			if err != nil {
 				log.Errorf("Could not hash received block: %v", err)
 			}
-			blockExists, err := ss.chainService.ContainsBlock(h)
+
+			blockExists, err := ss.chainService.ContainsBlock(blockHash)
 			if err != nil {
 				log.Errorf("Can not check for block in DB: %v", err)
 				continue
@@ -171,9 +177,30 @@ func (ss *Service) run() {
 			if blockExists {
 				continue
 			}
-			log.WithField("blockHash", fmt.Sprintf("0x%x", h)).Debug("Sending newly received block to subscribers")
-			// We send out a message over a feed.
+
+			// Verify attestation coming from proposer then forward block to the subscribers.
+			attestation := types.NewAttestation(response.Attestation)
+			cState := ss.chainService.CurrentCrystallizedState()
+			parentSlot, err := ss.chainService.GetBlockSlotNumber(block.ParentHash())
+			if err != nil {
+				log.Errorf("Failed to get parent slot: %v", err)
+				continue
+			}
+			proposerShardID, _, err := casper.GetProposerIndexAndShard(cState.ShardAndCommitteesForSlots(), cState.LastStateRecalc(), parentSlot)
+			if err != nil {
+				log.Errorf("Failed to get proposer shard ID: %v", err)
+				continue
+			}
+			if err := attestation.VerifyAttestation(proposerShardID); err != nil {
+				log.Errorf("Failed to verify proposer attestation: %v", err)
+				continue
+			}
+
+			log.WithField("blockHash", fmt.Sprintf("0x%x", blockHash)).Debug("Sending newly received block to subscribers")
 			ss.chainService.IncomingBlockFeed().Send(block)
+			log.WithField("attestationHash", fmt.Sprintf("0x%x", attestation.Key())).Debug("Sending newly received attestation to subscribers")
+			ss.chainService.IncomingAttestationFeed().Send(attestation)
+
 		case msg := <-ss.blockRequestBySlot:
 			request, ok := msg.Data.(*pb.BeaconBlockRequestBySlotNumber)
 			if !ok {
diff --git a/beacon-chain/sync/service_test.go b/beacon-chain/sync/service_test.go
index f44f53b930..fdf41ee557 100644
--- a/beacon-chain/sync/service_test.go
+++ b/beacon-chain/sync/service_test.go
@@ -3,6 +3,7 @@ package sync
 import (
 	"context"
 	"errors"
+	"fmt"
 	"io/ioutil"
 	"testing"
 
@@ -52,6 +53,22 @@ func (ms *mockChainService) IncomingBlockFeed() *event.Feed {
 	return new(event.Feed)
 }
 
+func (ms *mockChainService) IncomingAttestationFeed() *event.Feed {
+	return new(event.Feed)
+}
+
+func (ms *mockChainService) CurrentCrystallizedState() *types.CrystallizedState {
+	cState, err := types.NewGenesisCrystallizedState()
+	if err != nil {
+		fmt.Println(err)
+	}
+	return cState
+}
+
+func (ms *mockChainService) GetBlockSlotNumber(h [32]byte) (uint64, error) {
+	return 0, nil
+}
+
 func (ms *mockChainService) CheckForCanonicalBlockBySlot(slotnumber uint64) (bool, error) {
 	if ms.checkError {
 		return ms.slotExists, errors.New("mock check canonical block error")
@@ -121,9 +138,15 @@ func TestProcessBlock(t *testing.T) {
 		PowChainRef: []byte{1, 2, 3, 4, 5},
 		ParentHash:  make([]byte, 32),
 	}
+	attestation := &pb.AggregatedAttestation{
+		Slot:           0,
+		ShardId:        0,
+		ShardBlockHash: []byte{'A'},
+	}
 
 	responseBlock := &pb.BeaconBlockResponse{
-		Block: data,
+		Block:       data,
+		Attestation: attestation,
 	}
 
 	msg := p2p.Message{
@@ -316,6 +339,10 @@ func (ms *mockEmptyChainService) IncomingBlockFeed() *event.Feed {
 	return new(event.Feed)
 }
 
+func (ms *mockEmptyChainService) IncomingAttestationFeed() *event.Feed {
+	return new(event.Feed)
+}
+
 func (ms *mockEmptyChainService) setState(flag bool) {
 	ms.hasStoredState = flag
 }
@@ -328,6 +355,14 @@ func (ms *mockEmptyChainService) GetCanonicalBlockBySlotNumber(slotnumber uint64
 	return nil, nil
 }
 
+func (ms *mockEmptyChainService) CurrentCrystallizedState() *types.CrystallizedState {
+	return types.NewCrystallizedState(nil)
+}
+
+func (ms *mockEmptyChainService) GetBlockSlotNumber(h [32]byte) (uint64, error) {
+	return 0, nil
+}
+
 func TestStartEmptyState(t *testing.T) {
 	hook := logTest.NewGlobal()
 	cfg := DefaultConfig()
diff --git a/beacon-chain/types/active_state.go b/beacon-chain/types/active_state.go
index 733fd4eb14..c26131f8fd 100644
--- a/beacon-chain/types/active_state.go
+++ b/beacon-chain/types/active_state.go
@@ -29,7 +29,7 @@ func NewGenesisActiveState() *ActiveState {
 
 	return &ActiveState{
 		data: &pb.ActiveState{
-			PendingAttestations: []*pb.AttestationRecord{},
+			PendingAttestations: []*pb.AggregatedAttestation{},
 			RecentBlockHashes:   recentBlockHashes,
 		},
 		blockVoteCache: make(map[[32]byte]*VoteCache),
@@ -65,7 +65,7 @@ func (a *ActiveState) Hash() ([32]byte, error) {
 }
 
 // PendingAttestations returns attestations that have not yet been processed.
-func (a *ActiveState) PendingAttestations() []*pb.AttestationRecord {
+func (a *ActiveState) PendingAttestations() []*pb.AggregatedAttestation {
 	return a.data.PendingAttestations
 }
 
@@ -89,9 +89,9 @@ func (a *ActiveState) GetBlockVoteCache() map[[32]byte]*VoteCache {
 	return a.blockVoteCache
 }
 
-func (a *ActiveState) calculateNewAttestations(add []*pb.AttestationRecord, lastStateRecalc uint64) []*pb.AttestationRecord {
+func (a *ActiveState) calculateNewAttestations(add []*pb.AggregatedAttestation, lastStateRecalc uint64) []*pb.AggregatedAttestation {
 	existing := a.data.PendingAttestations
-	update := []*pb.AttestationRecord{}
+	update := []*pb.AggregatedAttestation{}
 	for i := 0; i < len(existing); i++ {
 		if existing[i].GetSlot() >= lastStateRecalc {
 			update = append(update, existing[i])
@@ -198,7 +198,7 @@ func (a *ActiveState) CalculateNewActiveState(block *Block, cState *Crystallized
 }
 
 // getSignedParentHashes returns all the parent hashes stored in active state up to last cycle length.
-func (a *ActiveState) getSignedParentHashes(block *Block, attestation *pb.AttestationRecord) [][32]byte {
+func (a *ActiveState) getSignedParentHashes(block *Block, attestation *pb.AggregatedAttestation) [][32]byte {
 	var signedParentHashes [][32]byte
 	start := block.SlotNumber() - attestation.Slot
 	end := block.SlotNumber() - attestation.Slot - uint64(len(attestation.ObliqueParentHashes)) + params.CycleLength
diff --git a/beacon-chain/types/active_state_test.go b/beacon-chain/types/active_state_test.go
index ccc8cc7cce..d685f0f7ea 100644
--- a/beacon-chain/types/active_state_test.go
+++ b/beacon-chain/types/active_state_test.go
@@ -26,7 +26,7 @@ func TestGenesisActiveState(t *testing.T) {
 func TestUpdateAttestations(t *testing.T) {
 	aState := NewGenesisActiveState()
 
-	newAttestations := []*pb.AttestationRecord{
+	newAttestations := []*pb.AggregatedAttestation{
 		{
 			Slot:    0,
 			ShardId: 0,
@@ -45,7 +45,7 @@ func TestUpdateAttestations(t *testing.T) {
 
 func TestUpdateAttestationsAfterRecalc(t *testing.T) {
 	aState := NewActiveState(&pb.ActiveState{
-		PendingAttestations: []*pb.AttestationRecord{
+		PendingAttestations: []*pb.AggregatedAttestation{
 			{
 				Slot:    0,
 				ShardId: 0,
@@ -57,7 +57,7 @@ func TestUpdateAttestationsAfterRecalc(t *testing.T) {
 		},
 	}, nil)
 
-	newAttestations := []*pb.AttestationRecord{
+	newAttestations := []*pb.AggregatedAttestation{
 		{
 			Slot:    10,
 			ShardId: 2,
@@ -138,7 +138,7 @@ func TestBlockVoteCache(t *testing.T) {
 	}
 	block := NewBlock(&pb.BeaconBlock{
 		SlotNumber: 1,
-		Attestations: []*pb.AttestationRecord{
+		Attestations: []*pb.AggregatedAttestation{
 			{
 				Slot:             0,
 				ShardId:          0,
@@ -185,7 +185,7 @@ func TestCalculateNewActiveState(t *testing.T) {
 	}
 
 	aState := NewActiveState(&pb.ActiveState{
-		PendingAttestations: []*pb.AttestationRecord{
+		PendingAttestations: []*pb.AggregatedAttestation{
 			{
 				Slot:    0,
 				ShardId: 0,
diff --git a/beacon-chain/types/attestation.go b/beacon-chain/types/attestation.go
index 3b5908b916..8655a4c1b6 100644
--- a/beacon-chain/types/attestation.go
+++ b/beacon-chain/types/attestation.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/golang/protobuf/proto"
+	"github.com/prysmaticlabs/prysm/beacon-chain/params"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	"golang.org/x/crypto/blake2b"
 )
@@ -13,15 +14,15 @@ import (
 // Attestation is the primary source of load on the beacon chain, it's used to
 // attest to some parent block in the chain and block hash in a shard.
 type Attestation struct {
-	data *pb.AttestationRecord
+	data *pb.AggregatedAttestation
 }
 
 // NewAttestation explicitly sets the data field of a attestation.
 // Return attestation with default fields if data is nil.
-func NewAttestation(data *pb.AttestationRecord) *Attestation {
+func NewAttestation(data *pb.AggregatedAttestation) *Attestation {
 	if data == nil {
 		return &Attestation{
-			data: &pb.AttestationRecord{
+			data: &pb.AggregatedAttestation{
 				Slot:                0,
 				ShardId:             0,
 				JustifiedSlot:       0,
@@ -37,7 +38,7 @@ func NewAttestation(data *pb.AttestationRecord) *Attestation {
 }
 
 // Proto returns the underlying protobuf data.
-func (a *Attestation) Proto() *pb.AttestationRecord {
+func (a *Attestation) Proto() *pb.AggregatedAttestation {
 	return a.data
 }
 
@@ -121,3 +122,43 @@ func (a *Attestation) ObliqueParentHashes() [][32]byte {
 func (a *Attestation) AggregateSig() []uint64 {
 	return a.data.AggregateSig
 }
+
+// VerifyAttestation verifies the proposer's attestation of the block.
+// Proposers broadcast the attestation along with the block to its peers.
+func (a *Attestation) VerifyAttestation(proposerShardID uint64) error {
+
+	// Verify the attestation attached with block response.
+	// Get proposer index and shardID.
+
+	attestationMsg := AttestationMsg(
+		a.ObliqueParentHashes(),
+		a.ShardBlockHash(),
+		a.SlotNumber(),
+		proposerShardID,
+		a.JustifiedSlotNumber())
+
+	log.Infof("Constructed attestation message for incoming block 0x%x", attestationMsg)
+
+	// TODO(#258): use attestationMsg to verify against signature and public key. Return error if incorrect.
+
+	log.Info("successfully verified attestation with incoming block")
+	return nil
+}
+
+// AttestationMsg hashes parentHashes + shardID + slotNumber + shardBlockHash + justifiedSlot
+// into a message to use for verifying with aggregated public key and signature.
+func AttestationMsg(parentHashes [][32]byte, blockHash []byte, slot uint64, shardID uint64, justifiedSlot uint64) [32]byte {
+	msg := make([]byte, binary.MaxVarintLen64)
+	binary.PutUvarint(msg, slot%params.CycleLength)
+	for _, parentHash := range parentHashes {
+		msg = append(msg, parentHash[:]...)
+	}
+	binary.PutUvarint(msg, shardID)
+	msg = append(msg, blockHash...)
+	binary.PutUvarint(msg, justifiedSlot)
+
+	var hashMsg [32]byte
+	h := blake2b.Sum512(msg)
+	copy(hashMsg[:], h[:32])
+	return hashMsg
+}
diff --git a/beacon-chain/types/attestation_test.go b/beacon-chain/types/attestation_test.go
index c9ba8d9878..7d6ff74775 100644
--- a/beacon-chain/types/attestation_test.go
+++ b/beacon-chain/types/attestation_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 func TestAttestation(t *testing.T) {
-	data := &pb.AttestationRecord{
+	data := &pb.AggregatedAttestation{
 		Slot:                0,
 		ShardId:             0,
 		JustifiedSlot:       0,
@@ -52,4 +52,7 @@ func TestAttestation(t *testing.T) {
 	if !bytes.Equal(attestation.ShardBlockHash(), []byte{0}) {
 		t.Errorf("mismatched shard block hash")
 	}
+	if err := attestation.VerifyAttestation(0); err != nil {
+		t.Errorf("verify attestation failed: %v", err)
+	}
 }
diff --git a/beacon-chain/types/block.go b/beacon-chain/types/block.go
index b6d196777f..a41f387342 100644
--- a/beacon-chain/types/block.go
+++ b/beacon-chain/types/block.go
@@ -2,7 +2,6 @@
 package types
 
 import (
-	"encoding/binary"
 	"fmt"
 	"time"
 
@@ -125,7 +124,7 @@ func (b *Block) AttestationCount() int {
 }
 
 // Attestations returns an array of attestations in the block.
-func (b *Block) Attestations() []*pb.AttestationRecord {
+func (b *Block) Attestations() []*pb.AggregatedAttestation {
 	return b.data.Attestations
 }
 
@@ -142,34 +141,49 @@ func (b *Block) isSlotValid() bool {
 	return clock.Now().After(validTimeThreshold)
 }
 
-// IsValid is called to decide if an incoming p2p block can be processed.
-// It checks the slot against the system clock, and the validity of the included attestations.
-// Existence of the parent block and the PoW chain block is checked outside of this function because they require additional dependencies.
+// IsValid is called to decide if an incoming p2p block can be processed. It checks for following conditions:
+// 1.) Ensure parent processed.
+// 2.) Ensure pow_chain_ref processed.
+// 3.) Ensure local time is large enough to process this block's slot.
+// 4.) Verify that the parent block's proposer's attestation is included.
 func (b *Block) IsValid(aState *ActiveState, cState *CrystallizedState, parentSlot uint64) bool {
 	_, err := b.Hash()
 	if err != nil {
-		log.Debugf("Could not hash incoming block: %v", err)
+		log.Errorf("Could not hash incoming block: %v", err)
 		return false
 	}
 
 	if b.SlotNumber() == 0 {
-		log.Debug("Can not process a genesis block")
+		log.Error("Can not process a genesis block")
 		return false
 	}
 
 	if !b.isSlotValid() {
-		log.Debugf("slot of block is too high: %d", b.SlotNumber())
+		log.Errorf("Slot of block is too high: %d", b.SlotNumber())
 		return false
 	}
 
+	// verify proposer from last slot is in one of the AggregatedAttestation.
+	var proposerAttested bool
+	_, proposerIndex, err := casper.GetProposerIndexAndShard(
+		cState.ShardAndCommitteesForSlots(),
+		cState.LastStateRecalc(),
+		parentSlot)
+	if err != nil {
+		log.Errorf("Can not get proposer index %v", err)
+		return false
+	}
 	for index, attestation := range b.Attestations() {
 		if !b.isAttestationValid(index, aState, cState, parentSlot) {
 			log.Debugf("attestation invalid: %v", attestation)
 			return false
 		}
+		if utils.BitSetCount(attestation.AttesterBitfield) == 1 && utils.CheckBit(attestation.AttesterBitfield, int(proposerIndex)) {
+			proposerAttested = true
+		}
 	}
 
-	return true
+	return proposerAttested
 }
 
 // isAttestationValid validates an attestation in a block.
@@ -207,26 +221,18 @@ func (b *Block) isAttestationValid(attestationIndex int, aState *ActiveState, cS
 
 	// TODO(#258): Generate validators aggregated pub key.
 
-	// Hash parentHashes + shardID + slotNumber + shardBlockHash into a message to use to
-	// to verify with aggregated public key and aggregated attestation signature.
-	msg := make([]byte, binary.MaxVarintLen64)
-	var signedHashesStr []byte
-	for _, parentHash := range parentHashes {
-		signedHashesStr = append(signedHashesStr, parentHash[:]...)
-		signedHashesStr = append(signedHashesStr, byte(' '))
-	}
-	binary.PutUvarint(msg, attestation.Slot%params.CycleLength)
-	msg = append(msg, signedHashesStr...)
-	binary.PutUvarint(msg, attestation.ShardId)
-	msg = append(msg, attestation.ShardBlockHash...)
-	binary.PutUvarint(msg, attestation.JustifiedSlot)
-
-	msgHash := blake2b.Sum512(msg)
+	attestationMsg := AttestationMsg(
+		parentHashes,
+		attestation.ShardBlockHash,
+		attestation.Slot,
+		attestation.ShardId,
+		attestation.JustifiedSlot)
 
 	log.Debugf("Attestation message for shard: %v, slot %v, block hash %v is: %v",
-		attestation.ShardId, attestation.Slot, attestation.ShardBlockHash, msgHash)
+		attestation.ShardId, attestation.Slot, attestation.ShardBlockHash, attestationMsg)
 
 	// TODO(#258): Verify msgHash against aggregated pub key and aggregated signature.
+
 	return true
 }
 
diff --git a/beacon-chain/types/block_test.go b/beacon-chain/types/block_test.go
index 7e25fdb277..ce0de9d04a 100644
--- a/beacon-chain/types/block_test.go
+++ b/beacon-chain/types/block_test.go
@@ -76,12 +76,12 @@ func TestBlockValidity(t *testing.T) {
 
 	b := NewBlock(&pb.BeaconBlock{
 		SlotNumber: 1,
-		Attestations: []*pb.AttestationRecord{
+		Attestations: []*pb.AggregatedAttestation{
 			{
 				Slot:             0,
 				ShardId:          0,
 				JustifiedSlot:    0,
-				AttesterBitfield: []byte{8, 8},
+				AttesterBitfield: []byte{64, 0},
 			},
 		},
 	})
diff --git a/beacon-chain/types/crystallized_state.go b/beacon-chain/types/crystallized_state.go
index 3d494e0ec4..5a774e8356 100644
--- a/beacon-chain/types/crystallized_state.go
+++ b/beacon-chain/types/crystallized_state.go
@@ -205,7 +205,7 @@ func (c *CrystallizedState) isDynastyTransition(slotNumber uint64) bool {
 }
 
 // getAttesterIndices fetches the attesters for a given attestation record.
-func (c *CrystallizedState) getAttesterIndices(attestation *pb.AttestationRecord) ([]uint32, error) {
+func (c *CrystallizedState) getAttesterIndices(attestation *pb.AggregatedAttestation) ([]uint32, error) {
 	slotsStart := int64(c.LastStateRecalc()) - params.CycleLength
 	slotIndex := (int64(attestation.Slot) - slotsStart) % params.CycleLength
 	// TODO(#267): ShardAndCommitteesForSlots will return default value because the spec for dynasty transition is not finalized.
@@ -351,7 +351,7 @@ func copyCrosslinks(existing []*pb.CrosslinkRecord) []*pb.CrosslinkRecord {
 // processCrosslinks checks if the proposed shard block has recevied
 // 2/3 of the votes. If yes, we update crosslink record to point to
 // the proposed shard block with latest dynasty and slot numbers.
-func (c *CrystallizedState) processCrosslinks(pendingAttestations []*pb.AttestationRecord, slot uint64) ([]*pb.CrosslinkRecord, error) {
+func (c *CrystallizedState) processCrosslinks(pendingAttestations []*pb.AggregatedAttestation, slot uint64) ([]*pb.CrosslinkRecord, error) {
 	validators := c.data.Validators
 	dynasty := c.data.CurrentDynasty
 	crosslinkRecords := copyCrosslinks(c.data.CrosslinkRecords)
diff --git a/beacon-chain/types/crystallized_state_test.go b/beacon-chain/types/crystallized_state_test.go
index b04ad9ec1e..bc6370f5f5 100644
--- a/beacon-chain/types/crystallized_state_test.go
+++ b/beacon-chain/types/crystallized_state_test.go
@@ -144,7 +144,7 @@ func TestProcessCrosslinks(t *testing.T) {
 	}
 
 	// Set up pending attestations.
-	pAttestations := []*pb.AttestationRecord{
+	pAttestations := []*pb.AggregatedAttestation{
 		{
 			Slot:             0,
 			ShardId:          0,
diff --git a/beacon-chain/types/interfaces.go b/beacon-chain/types/interfaces.go
index 782b6478b7..9d45b644fa 100644
--- a/beacon-chain/types/interfaces.go
+++ b/beacon-chain/types/interfaces.go
@@ -38,6 +38,7 @@ type BlockChainService interface {
 	HasStoredState() (bool, error)
 	ContainsBlock(h [32]byte) (bool, error)
 	SaveBlock(b *Block) error
+	GetBlockSlotNumber(h [32]byte) (uint64, error)
 }
 
 // CrystallizedStateChainService is the interface for crystallized state related functions in local beacon chain.
diff --git a/beacon-chain/utils/checkbit.go b/beacon-chain/utils/checkbit.go
index 7d9a4ce2a8..60950145ac 100644
--- a/beacon-chain/utils/checkbit.go
+++ b/beacon-chain/utils/checkbit.go
@@ -16,13 +16,17 @@ func CheckBit(bitfield []byte, index int) bool {
 
 // BitSetCount counts the number of 1s in a byte using the following algo:
 // https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
-func BitSetCount(v byte) byte {
-	v = (v & 0x55) + ((v >> 1) & 0x55)
-	v = (v & 0x33) + ((v >> 2) & 0x33)
-	return (v + (v >> 4)) & 0xF
+func BitSetCount(bytes []byte) int {
+	var total int
+	for _, b := range bytes {
+		b = (b & 0x55) + ((b >> 1) & 0x55)
+		b = (b & 0x33) + ((b >> 2) & 0x33)
+		total += int((b + (b >> 4)) & 0xF)
+	}
+	return total
 }
 
-// BitLength returns the length of the bitfield for a given number of attesters in bytes.
+// BitLength returns the length of the bitfield for a giben number of attesters in bytes.
 func BitLength(b int) int {
 	return (b + 7) / 8
 }
diff --git a/beacon-chain/utils/checkbit_test.go b/beacon-chain/utils/checkbit_test.go
index b96e5d3691..7bd76106a4 100644
--- a/beacon-chain/utils/checkbit_test.go
+++ b/beacon-chain/utils/checkbit_test.go
@@ -36,8 +36,8 @@ func TestBitSetCount(t *testing.T) {
 		{a: 49, b: 3},  //00110001
 	}
 	for _, tt := range tests {
-		if int(BitSetCount(tt.a)) != tt.b {
-			t.Errorf("BitSetCount(%d) = %v, want = %d", tt.a, int(BitSetCount(tt.a)), tt.b)
+		if int(BitSetCount([]byte{tt.a})) != tt.b {
+			t.Errorf("BitSetCount(%d) = %v, want = %d", tt.a, int(BitSetCount([]byte{tt.a})), tt.b)
 		}
 	}
 }
diff --git a/proto/README.md b/proto/README.md
index d5466c8198..2b5ba0e4e1 100644
--- a/proto/README.md
+++ b/proto/README.md
@@ -26,4 +26,4 @@ For example, when we build the testing go proto library
 generated at 
 `bazel-bin/proto/testing/linux_amd64_stripped/ethereum_testing_go_proto\~/github.com/prysmaticlabs/prysm/proto/testing/test.pb.go`.
 This generated file can be copied, or you can use you protoc locally if you
-prefer.
\ No newline at end of file
+prefer.
diff --git a/proto/beacon/p2p/v1/messages.pb.go b/proto/beacon/p2p/v1/messages.pb.go
index 316f87a9f6..4b3defc3c9 100644
--- a/proto/beacon/p2p/v1/messages.pb.go
+++ b/proto/beacon/p2p/v1/messages.pb.go
@@ -66,7 +66,7 @@ func (x Topic) String() string {
 	return proto.EnumName(Topic_name, int32(x))
 }
 func (Topic) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{0}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{0}
 }
 
 type BeaconBlockHashAnnounce struct {
@@ -80,7 +80,7 @@ func (m *BeaconBlockHashAnnounce) Reset()         { *m = BeaconBlockHashAnnounce
 func (m *BeaconBlockHashAnnounce) String() string { return proto.CompactTextString(m) }
 func (*BeaconBlockHashAnnounce) ProtoMessage()    {}
 func (*BeaconBlockHashAnnounce) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{0}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{0}
 }
 func (m *BeaconBlockHashAnnounce) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_BeaconBlockHashAnnounce.Unmarshal(m, b)
@@ -118,7 +118,7 @@ func (m *BeaconBlockRequest) Reset()         { *m = BeaconBlockRequest{} }
 func (m *BeaconBlockRequest) String() string { return proto.CompactTextString(m) }
 func (*BeaconBlockRequest) ProtoMessage()    {}
 func (*BeaconBlockRequest) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{1}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{1}
 }
 func (m *BeaconBlockRequest) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_BeaconBlockRequest.Unmarshal(m, b)
@@ -156,7 +156,7 @@ func (m *BeaconBlockRequestBySlotNumber) Reset()         { *m = BeaconBlockReque
 func (m *BeaconBlockRequestBySlotNumber) String() string { return proto.CompactTextString(m) }
 func (*BeaconBlockRequestBySlotNumber) ProtoMessage()    {}
 func (*BeaconBlockRequestBySlotNumber) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{2}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{2}
 }
 func (m *BeaconBlockRequestBySlotNumber) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_BeaconBlockRequestBySlotNumber.Unmarshal(m, b)
@@ -184,17 +184,18 @@ func (m *BeaconBlockRequestBySlotNumber) GetSlotNumber() uint64 {
 }
 
 type BeaconBlockResponse struct {
-	Block                *BeaconBlock `protobuf:"bytes,1,opt,name=block,proto3" json:"block,omitempty"`
-	XXX_NoUnkeyedLiteral struct{}     `json:"-"`
-	XXX_unrecognized     []byte       `json:"-"`
-	XXX_sizecache        int32        `json:"-"`
+	Block                *BeaconBlock           `protobuf:"bytes,1,opt,name=block,proto3" json:"block,omitempty"`
+	Attestation          *AggregatedAttestation `protobuf:"bytes,2,opt,name=attestation,proto3" json:"attestation,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}               `json:"-"`
+	XXX_unrecognized     []byte                 `json:"-"`
+	XXX_sizecache        int32                  `json:"-"`
 }
 
 func (m *BeaconBlockResponse) Reset()         { *m = BeaconBlockResponse{} }
 func (m *BeaconBlockResponse) String() string { return proto.CompactTextString(m) }
 func (*BeaconBlockResponse) ProtoMessage()    {}
 func (*BeaconBlockResponse) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{3}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{3}
 }
 func (m *BeaconBlockResponse) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_BeaconBlockResponse.Unmarshal(m, b)
@@ -221,25 +222,32 @@ func (m *BeaconBlockResponse) GetBlock() *BeaconBlock {
 	return nil
 }
 
+func (m *BeaconBlockResponse) GetAttestation() *AggregatedAttestation {
+	if m != nil {
+		return m.Attestation
+	}
+	return nil
+}
+
 type BeaconBlock struct {
-	ParentHash            []byte               `protobuf:"bytes,1,opt,name=parent_hash,json=parentHash,proto3" json:"parent_hash,omitempty"`
-	SlotNumber            uint64               `protobuf:"varint,2,opt,name=slot_number,json=slotNumber,proto3" json:"slot_number,omitempty"`
-	RandaoReveal          []byte               `protobuf:"bytes,3,opt,name=randao_reveal,json=randaoReveal,proto3" json:"randao_reveal,omitempty"`
-	PowChainRef           []byte               `protobuf:"bytes,4,opt,name=pow_chain_ref,json=powChainRef,proto3" json:"pow_chain_ref,omitempty"`
-	ActiveStateHash       []byte               `protobuf:"bytes,5,opt,name=active_state_hash,json=activeStateHash,proto3" json:"active_state_hash,omitempty"`
-	CrystallizedStateHash []byte               `protobuf:"bytes,6,opt,name=crystallized_state_hash,json=crystallizedStateHash,proto3" json:"crystallized_state_hash,omitempty"`
-	Timestamp             *timestamp.Timestamp `protobuf:"bytes,7,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
-	Attestations          []*AttestationRecord `protobuf:"bytes,8,rep,name=attestations,proto3" json:"attestations,omitempty"`
-	XXX_NoUnkeyedLiteral  struct{}             `json:"-"`
-	XXX_unrecognized      []byte               `json:"-"`
-	XXX_sizecache         int32                `json:"-"`
+	ParentHash            []byte                   `protobuf:"bytes,1,opt,name=parent_hash,json=parentHash,proto3" json:"parent_hash,omitempty"`
+	SlotNumber            uint64                   `protobuf:"varint,2,opt,name=slot_number,json=slotNumber,proto3" json:"slot_number,omitempty"`
+	RandaoReveal          []byte                   `protobuf:"bytes,3,opt,name=randao_reveal,json=randaoReveal,proto3" json:"randao_reveal,omitempty"`
+	PowChainRef           []byte                   `protobuf:"bytes,4,opt,name=pow_chain_ref,json=powChainRef,proto3" json:"pow_chain_ref,omitempty"`
+	ActiveStateHash       []byte                   `protobuf:"bytes,5,opt,name=active_state_hash,json=activeStateHash,proto3" json:"active_state_hash,omitempty"`
+	CrystallizedStateHash []byte                   `protobuf:"bytes,6,opt,name=crystallized_state_hash,json=crystallizedStateHash,proto3" json:"crystallized_state_hash,omitempty"`
+	Timestamp             *timestamp.Timestamp     `protobuf:"bytes,7,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
+	Attestations          []*AggregatedAttestation `protobuf:"bytes,8,rep,name=attestations,proto3" json:"attestations,omitempty"`
+	XXX_NoUnkeyedLiteral  struct{}                 `json:"-"`
+	XXX_unrecognized      []byte                   `json:"-"`
+	XXX_sizecache         int32                    `json:"-"`
 }
 
 func (m *BeaconBlock) Reset()         { *m = BeaconBlock{} }
 func (m *BeaconBlock) String() string { return proto.CompactTextString(m) }
 func (*BeaconBlock) ProtoMessage()    {}
 func (*BeaconBlock) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{4}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{4}
 }
 func (m *BeaconBlock) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_BeaconBlock.Unmarshal(m, b)
@@ -308,7 +316,7 @@ func (m *BeaconBlock) GetTimestamp() *timestamp.Timestamp {
 	return nil
 }
 
-func (m *BeaconBlock) GetAttestations() []*AttestationRecord {
+func (m *BeaconBlock) GetAttestations() []*AggregatedAttestation {
 	if m != nil {
 		return m.Attestations
 	}
@@ -326,7 +334,7 @@ func (m *CrystallizedStateHashAnnounce) Reset()         { *m = CrystallizedState
 func (m *CrystallizedStateHashAnnounce) String() string { return proto.CompactTextString(m) }
 func (*CrystallizedStateHashAnnounce) ProtoMessage()    {}
 func (*CrystallizedStateHashAnnounce) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{5}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{5}
 }
 func (m *CrystallizedStateHashAnnounce) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_CrystallizedStateHashAnnounce.Unmarshal(m, b)
@@ -364,7 +372,7 @@ func (m *CrystallizedStateRequest) Reset()         { *m = CrystallizedStateReque
 func (m *CrystallizedStateRequest) String() string { return proto.CompactTextString(m) }
 func (*CrystallizedStateRequest) ProtoMessage()    {}
 func (*CrystallizedStateRequest) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{6}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{6}
 }
 func (m *CrystallizedStateRequest) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_CrystallizedStateRequest.Unmarshal(m, b)
@@ -402,7 +410,7 @@ func (m *CrystallizedStateResponse) Reset()         { *m = CrystallizedStateResp
 func (m *CrystallizedStateResponse) String() string { return proto.CompactTextString(m) }
 func (*CrystallizedStateResponse) ProtoMessage()    {}
 func (*CrystallizedStateResponse) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{7}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{7}
 }
 func (m *CrystallizedStateResponse) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_CrystallizedStateResponse.Unmarshal(m, b)
@@ -450,7 +458,7 @@ func (m *CrystallizedState) Reset()         { *m = CrystallizedState{} }
 func (m *CrystallizedState) String() string { return proto.CompactTextString(m) }
 func (*CrystallizedState) ProtoMessage()    {}
 func (*CrystallizedState) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{8}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{8}
 }
 func (m *CrystallizedState) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_CrystallizedState.Unmarshal(m, b)
@@ -558,7 +566,7 @@ func (m *ShardAndCommitteeArray) Reset()         { *m = ShardAndCommitteeArray{}
 func (m *ShardAndCommitteeArray) String() string { return proto.CompactTextString(m) }
 func (*ShardAndCommitteeArray) ProtoMessage()    {}
 func (*ShardAndCommitteeArray) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{9}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{9}
 }
 func (m *ShardAndCommitteeArray) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ShardAndCommitteeArray.Unmarshal(m, b)
@@ -596,7 +604,7 @@ func (m *ActiveStateHashAnnounce) Reset()         { *m = ActiveStateHashAnnounce
 func (m *ActiveStateHashAnnounce) String() string { return proto.CompactTextString(m) }
 func (*ActiveStateHashAnnounce) ProtoMessage()    {}
 func (*ActiveStateHashAnnounce) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{10}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{10}
 }
 func (m *ActiveStateHashAnnounce) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ActiveStateHashAnnounce.Unmarshal(m, b)
@@ -634,7 +642,7 @@ func (m *ActiveStateRequest) Reset()         { *m = ActiveStateRequest{} }
 func (m *ActiveStateRequest) String() string { return proto.CompactTextString(m) }
 func (*ActiveStateRequest) ProtoMessage()    {}
 func (*ActiveStateRequest) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{11}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{11}
 }
 func (m *ActiveStateRequest) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ActiveStateRequest.Unmarshal(m, b)
@@ -673,7 +681,7 @@ func (m *ShardAndCommittee) Reset()         { *m = ShardAndCommittee{} }
 func (m *ShardAndCommittee) String() string { return proto.CompactTextString(m) }
 func (*ShardAndCommittee) ProtoMessage()    {}
 func (*ShardAndCommittee) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{12}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{12}
 }
 func (m *ShardAndCommittee) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ShardAndCommittee.Unmarshal(m, b)
@@ -718,7 +726,7 @@ func (m *ActiveStateResponse) Reset()         { *m = ActiveStateResponse{} }
 func (m *ActiveStateResponse) String() string { return proto.CompactTextString(m) }
 func (*ActiveStateResponse) ProtoMessage()    {}
 func (*ActiveStateResponse) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{13}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{13}
 }
 func (m *ActiveStateResponse) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ActiveStateResponse.Unmarshal(m, b)
@@ -746,18 +754,18 @@ func (m *ActiveStateResponse) GetActiveState() *ActiveState {
 }
 
 type ActiveState struct {
-	PendingAttestations  []*AttestationRecord `protobuf:"bytes,1,rep,name=pending_attestations,json=pendingAttestations,proto3" json:"pending_attestations,omitempty"`
-	RecentBlockHashes    [][]byte             `protobuf:"bytes,2,rep,name=recent_block_hashes,json=recentBlockHashes,proto3" json:"recent_block_hashes,omitempty"`
-	XXX_NoUnkeyedLiteral struct{}             `json:"-"`
-	XXX_unrecognized     []byte               `json:"-"`
-	XXX_sizecache        int32                `json:"-"`
+	PendingAttestations  []*AggregatedAttestation `protobuf:"bytes,1,rep,name=pending_attestations,json=pendingAttestations,proto3" json:"pending_attestations,omitempty"`
+	RecentBlockHashes    [][]byte                 `protobuf:"bytes,2,rep,name=recent_block_hashes,json=recentBlockHashes,proto3" json:"recent_block_hashes,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}                 `json:"-"`
+	XXX_unrecognized     []byte                   `json:"-"`
+	XXX_sizecache        int32                    `json:"-"`
 }
 
 func (m *ActiveState) Reset()         { *m = ActiveState{} }
 func (m *ActiveState) String() string { return proto.CompactTextString(m) }
 func (*ActiveState) ProtoMessage()    {}
 func (*ActiveState) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{14}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{14}
 }
 func (m *ActiveState) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ActiveState.Unmarshal(m, b)
@@ -777,7 +785,7 @@ func (m *ActiveState) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_ActiveState proto.InternalMessageInfo
 
-func (m *ActiveState) GetPendingAttestations() []*AttestationRecord {
+func (m *ActiveState) GetPendingAttestations() []*AggregatedAttestation {
 	if m != nil {
 		return m.PendingAttestations
 	}
@@ -808,7 +816,7 @@ func (m *ValidatorRecord) Reset()         { *m = ValidatorRecord{} }
 func (m *ValidatorRecord) String() string { return proto.CompactTextString(m) }
 func (*ValidatorRecord) ProtoMessage()    {}
 func (*ValidatorRecord) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{15}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{15}
 }
 func (m *ValidatorRecord) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_ValidatorRecord.Unmarshal(m, b)
@@ -877,7 +885,7 @@ func (m *ValidatorRecord) GetEndDynasty() uint64 {
 	return 0
 }
 
-type AttestationRecord struct {
+type AggregatedAttestation struct {
 	Slot                 uint64   `protobuf:"varint,1,opt,name=slot,proto3" json:"slot,omitempty"`
 	ShardId              uint64   `protobuf:"varint,2,opt,name=shard_id,json=shardId,proto3" json:"shard_id,omitempty"`
 	JustifiedSlot        uint64   `protobuf:"varint,3,opt,name=justified_slot,json=justifiedSlot,proto3" json:"justified_slot,omitempty"`
@@ -891,80 +899,80 @@ type AttestationRecord struct {
 	XXX_sizecache        int32    `json:"-"`
 }
 
-func (m *AttestationRecord) Reset()         { *m = AttestationRecord{} }
-func (m *AttestationRecord) String() string { return proto.CompactTextString(m) }
-func (*AttestationRecord) ProtoMessage()    {}
-func (*AttestationRecord) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{16}
+func (m *AggregatedAttestation) Reset()         { *m = AggregatedAttestation{} }
+func (m *AggregatedAttestation) String() string { return proto.CompactTextString(m) }
+func (*AggregatedAttestation) ProtoMessage()    {}
+func (*AggregatedAttestation) Descriptor() ([]byte, []int) {
+	return fileDescriptor_messages_facf6369f1deca1c, []int{16}
 }
-func (m *AttestationRecord) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_AttestationRecord.Unmarshal(m, b)
+func (m *AggregatedAttestation) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_AggregatedAttestation.Unmarshal(m, b)
 }
-func (m *AttestationRecord) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_AttestationRecord.Marshal(b, m, deterministic)
+func (m *AggregatedAttestation) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_AggregatedAttestation.Marshal(b, m, deterministic)
 }
-func (dst *AttestationRecord) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_AttestationRecord.Merge(dst, src)
+func (dst *AggregatedAttestation) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_AggregatedAttestation.Merge(dst, src)
 }
-func (m *AttestationRecord) XXX_Size() int {
-	return xxx_messageInfo_AttestationRecord.Size(m)
+func (m *AggregatedAttestation) XXX_Size() int {
+	return xxx_messageInfo_AggregatedAttestation.Size(m)
 }
-func (m *AttestationRecord) XXX_DiscardUnknown() {
-	xxx_messageInfo_AttestationRecord.DiscardUnknown(m)
+func (m *AggregatedAttestation) XXX_DiscardUnknown() {
+	xxx_messageInfo_AggregatedAttestation.DiscardUnknown(m)
 }
 
-var xxx_messageInfo_AttestationRecord proto.InternalMessageInfo
+var xxx_messageInfo_AggregatedAttestation proto.InternalMessageInfo
 
-func (m *AttestationRecord) GetSlot() uint64 {
+func (m *AggregatedAttestation) GetSlot() uint64 {
 	if m != nil {
 		return m.Slot
 	}
 	return 0
 }
 
-func (m *AttestationRecord) GetShardId() uint64 {
+func (m *AggregatedAttestation) GetShardId() uint64 {
 	if m != nil {
 		return m.ShardId
 	}
 	return 0
 }
 
-func (m *AttestationRecord) GetJustifiedSlot() uint64 {
+func (m *AggregatedAttestation) GetJustifiedSlot() uint64 {
 	if m != nil {
 		return m.JustifiedSlot
 	}
 	return 0
 }
 
-func (m *AttestationRecord) GetJustifiedBlockHash() []byte {
+func (m *AggregatedAttestation) GetJustifiedBlockHash() []byte {
 	if m != nil {
 		return m.JustifiedBlockHash
 	}
 	return nil
 }
 
-func (m *AttestationRecord) GetShardBlockHash() []byte {
+func (m *AggregatedAttestation) GetShardBlockHash() []byte {
 	if m != nil {
 		return m.ShardBlockHash
 	}
 	return nil
 }
 
-func (m *AttestationRecord) GetAttesterBitfield() []byte {
+func (m *AggregatedAttestation) GetAttesterBitfield() []byte {
 	if m != nil {
 		return m.AttesterBitfield
 	}
 	return nil
 }
 
-func (m *AttestationRecord) GetObliqueParentHashes() [][]byte {
+func (m *AggregatedAttestation) GetObliqueParentHashes() [][]byte {
 	if m != nil {
 		return m.ObliqueParentHashes
 	}
 	return nil
 }
 
-func (m *AttestationRecord) GetAggregateSig() []uint64 {
+func (m *AggregatedAttestation) GetAggregateSig() []uint64 {
 	if m != nil {
 		return m.AggregateSig
 	}
@@ -984,7 +992,7 @@ func (m *CrosslinkRecord) Reset()         { *m = CrosslinkRecord{} }
 func (m *CrosslinkRecord) String() string { return proto.CompactTextString(m) }
 func (*CrosslinkRecord) ProtoMessage()    {}
 func (*CrosslinkRecord) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{17}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{17}
 }
 func (m *CrosslinkRecord) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_CrosslinkRecord.Unmarshal(m, b)
@@ -1036,7 +1044,7 @@ func (m *AttestationHashes) Reset()         { *m = AttestationHashes{} }
 func (m *AttestationHashes) String() string { return proto.CompactTextString(m) }
 func (*AttestationHashes) ProtoMessage()    {}
 func (*AttestationHashes) Descriptor() ([]byte, []int) {
-	return fileDescriptor_messages_e19f4492e67c7db5, []int{18}
+	return fileDescriptor_messages_facf6369f1deca1c, []int{18}
 }
 func (m *AttestationHashes) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_AttestationHashes.Unmarshal(m, b)
@@ -1080,96 +1088,97 @@ func init() {
 	proto.RegisterType((*ActiveStateResponse)(nil), "ethereum.beacon.p2p.v1.ActiveStateResponse")
 	proto.RegisterType((*ActiveState)(nil), "ethereum.beacon.p2p.v1.ActiveState")
 	proto.RegisterType((*ValidatorRecord)(nil), "ethereum.beacon.p2p.v1.ValidatorRecord")
-	proto.RegisterType((*AttestationRecord)(nil), "ethereum.beacon.p2p.v1.AttestationRecord")
+	proto.RegisterType((*AggregatedAttestation)(nil), "ethereum.beacon.p2p.v1.AggregatedAttestation")
 	proto.RegisterType((*CrosslinkRecord)(nil), "ethereum.beacon.p2p.v1.CrosslinkRecord")
 	proto.RegisterType((*AttestationHashes)(nil), "ethereum.beacon.p2p.v1.AttestationHashes")
 	proto.RegisterEnum("ethereum.beacon.p2p.v1.Topic", Topic_name, Topic_value)
 }
 
-func init() { proto.RegisterFile("messages.proto", fileDescriptor_messages_e19f4492e67c7db5) }
+func init() { proto.RegisterFile("messages.proto", fileDescriptor_messages_facf6369f1deca1c) }
 
-var fileDescriptor_messages_e19f4492e67c7db5 = []byte{
-	// 1297 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x94, 0x56, 0x5f, 0x6f, 0xdb, 0x36,
-	0x10, 0x5f, 0x6c, 0xa7, 0x4e, 0xce, 0x4e, 0x62, 0x33, 0xfd, 0xa3, 0x64, 0x6b, 0x93, 0xa9, 0x2b,
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+	0xc2, 0xd4, 0x94, 0xf8, 0xd3, 0x08, 0x73, 0x31, 0x55, 0x7d, 0x59, 0xb4, 0xb7, 0x34, 0xfc, 0x34,
+	0x46, 0xd1, 0x5d, 0xd8, 0x12, 0x54, 0xe0, 0xd0, 0xf5, 0xc9, 0x98, 0xf2, 0x40, 0x70, 0xd5, 0x8d,
+	0x45, 0x7b, 0x53, 0xa1, 0x4f, 0x35, 0x88, 0xfe, 0x0b, 0x15, 0x6d, 0xc7, 0xe5, 0x84, 0xf8, 0xaa,
+	0x11, 0x2b, 0x76, 0x59, 0x63, 0x0e, 0x21, 0xbe, 0x9c, 0xaa, 0x94, 0x22, 0x30, 0x13, 0xc6, 0xba,
+	0x32, 0x94, 0xe8, 0x39, 0x12, 0x43, 0x5d, 0xa8, 0x79, 0x8c, 0x72, 0x1e, 0x06, 0xd1, 0x99, 0xcc,
+	0x26, 0x65, 0x3e, 0x37, 0x36, 0x54, 0x63, 0xde, 0xbb, 0xbc, 0x7a, 0x5a, 0xc1, 0x56, 0x7c, 0xbb,
+	0xea, 0xcd, 0x03, 0x1c, 0x7d, 0x09, 0x70, 0x8e, 0xc3, 0xc0, 0xc7, 0x82, 0x32, 0x6e, 0xc0, 0xd5,
+	0xe6, 0xde, 0x24, 0x4c, 0x6d, 0x2e, 0xa3, 0x8a, 0x18, 0xdc, 0xe6, 0x43, 0xcc, 0x7c, 0x17, 0x47,
+	0xbe, 0xeb, 0xd1, 0xd1, 0x28, 0x10, 0x82, 0x10, 0xee, 0xf6, 0x29, 0x53, 0x09, 0xe7, 0x46, 0x59,
+	0x19, 0xaf, 0x5f, 0x66, 0xdc, 0x91, 0xda, 0x56, 0xe4, 0x37, 0x13, 0x5d, 0x8b, 0x31, 0x3c, 0xb5,
+	0xf7, 0xf9, 0x22, 0xce, 0x9f, 0x51, 0x26, 0x2b, 0xc5, 0xcd, 0x1f, 0xe1, 0xc6, 0x6a, 0x2d, 0xe4,
+	0xc3, 0x1e, 0x96, 0x1f, 0xee, 0x0a, 0x9f, 0x8c, 0x9c, 0x72, 0xe4, 0xf8, 0x2f, 0x3b, 0x62, 0xdf,
+	0x50, 0xb6, 0x96, 0x70, 0x79, 0x3f, 0x59, 0xf3, 0xbb, 0xea, 0x63, 0xf7, 0x53, 0x86, 0x7e, 0xd5,
+	0x1c, 0x9f, 0x40, 0x6d, 0xe9, 0x34, 0xb4, 0x07, 0xeb, 0x71, 0x34, 0x81, 0xaf, 0xc7, 0xa8, 0xa4,
+	0xfe, 0x5f, 0xf8, 0xe8, 0x3f, 0xb0, 0x31, 0x0b, 0x2f, 0x7f, 0x58, 0x38, 0xda, 0xb4, 0x67, 0x80,
+	0xf9, 0x0e, 0x76, 0xe6, 0xce, 0xd5, 0xfb, 0xe0, 0x19, 0x54, 0xb2, 0x2b, 0xf8, 0x63, 0x17, 0x56,
+	0xd6, 0x44, 0x39, 0xb3, 0xa2, 0xcd, 0x5f, 0x72, 0x50, 0xce, 0x08, 0xd1, 0xf7, 0x70, 0x7d, 0x4c,
+	0x22, 0x3f, 0x88, 0x06, 0xee, 0xdc, 0x12, 0xcd, 0xfd, 0x93, 0x25, 0xba, 0xa3, 0x4d, 0x65, 0x30,
+	0x2e, 0x47, 0x9a, 0x11, 0x4f, 0x4e, 0xa8, 0xba, 0x38, 0xd5, 0x55, 0x40, 0xb8, 0x0a, 0xbc, 0x62,
+	0xd7, 0x62, 0x51, 0xfa, 0x64, 0x20, 0xdc, 0xfc, 0x39, 0x0f, 0xdb, 0x0b, 0xbd, 0x8b, 0x6e, 0x01,
+	0x8c, 0x27, 0xbd, 0x30, 0xf0, 0xdc, 0x33, 0x32, 0xd5, 0xf9, 0xdc, 0x88, 0x91, 0x97, 0x64, 0x2a,
+	0x17, 0xd2, 0x45, 0x20, 0x86, 0x3e, 0xc3, 0x17, 0x38, 0x8c, 0xbb, 0x28, 0x59, 0x48, 0x33, 0x5c,
+	0xd5, 0x08, 0x3d, 0x04, 0x94, 0xa1, 0x62, 0xdf, 0x67, 0x84, 0x73, 0x7d, 0x31, 0xd6, 0x66, 0x12,
+	0x2b, 0x16, 0xa0, 0x07, 0x50, 0xd3, 0x57, 0x68, 0x5c, 0xa1, 0x11, 0x89, 0x84, 0xbe, 0x21, 0xab,
+	0xb1, 0xa0, 0x99, 0xe2, 0xc8, 0x80, 0x52, 0x0f, 0x87, 0x38, 0xf2, 0x88, 0x5e, 0x42, 0xc9, 0xaf,
+	0xdc, 0x19, 0x6a, 0x57, 0xa4, 0x4b, 0x2a, 0x5e, 0x3e, 0x15, 0x05, 0x26, 0x2b, 0xea, 0x00, 0xca,
+	0x24, 0xf2, 0x53, 0x4a, 0x29, 0xbe, 0xcf, 0x49, 0xe4, 0x6b, 0x82, 0xf9, 0x7b, 0x1e, 0x76, 0x57,
+	0x26, 0x5e, 0xb6, 0xa5, 0xda, 0x93, 0x71, 0x66, 0xd4, 0xf7, 0x5c, 0x07, 0xe6, 0xe7, 0x3b, 0xf0,
+	0x2e, 0x6c, 0xad, 0x5c, 0xc8, 0x9b, 0xef, 0xe7, 0x96, 0xf1, 0xff, 0xe1, 0xfa, 0x8c, 0x36, 0x2b,
+	0x9e, 0x8e, 0x1f, 0xa5, 0xb2, 0xb4, 0x7a, 0xe8, 0x08, 0xaa, 0xf1, 0x99, 0x19, 0x76, 0xfc, 0x4e,
+	0xd8, 0x52, 0xf8, 0x8c, 0xf9, 0x00, 0x6a, 0x71, 0xbf, 0x11, 0xe6, 0xf6, 0x02, 0xd1, 0x0f, 0x48,
+	0xe8, 0xeb, 0x07, 0x42, 0x35, 0x11, 0x34, 0x34, 0x8e, 0x1e, 0xc3, 0x2e, 0xed, 0x85, 0xc1, 0x87,
+	0x09, 0x71, 0x33, 0x4f, 0x22, 0xc2, 0x8d, 0x92, 0x6a, 0xa2, 0x1d, 0x2d, 0x7c, 0x95, 0xbe, 0x8d,
+	0x08, 0x97, 0x29, 0xc7, 0x49, 0xae, 0x5c, 0x1e, 0x0c, 0xd4, 0xb3, 0xa0, 0x68, 0x57, 0x52, 0xd0,
+	0x09, 0x06, 0xe6, 0x3b, 0xd8, 0x5e, 0xd8, 0xba, 0xb2, 0x88, 0x49, 0x05, 0xf4, 0xdc, 0xea, 0x5f,
+	0x39, 0xb7, 0x2a, 0x2c, 0x15, 0x55, 0x5e, 0xb9, 0x3a, 0x03, 0xd2, 0x12, 0x14, 0x66, 0x25, 0x30,
+	0xbf, 0x80, 0x5a, 0xa6, 0x4a, 0xda, 0xb1, 0x63, 0xa8, 0x66, 0x26, 0x2d, 0x79, 0xdc, 0x15, 0xd4,
+	0x5b, 0x6a, 0x9e, 0x7c, 0xff, 0xb7, 0x3c, 0xac, 0x75, 0xe9, 0x38, 0xf0, 0x50, 0x19, 0x4a, 0xa7,
+	0xed, 0x97, 0xed, 0xce, 0x37, 0xed, 0xea, 0xbf, 0xd0, 0x6d, 0xd8, 0x6f, 0xb4, 0xac, 0x66, 0xa7,
+	0xed, 0x36, 0x4e, 0x3a, 0xcd, 0x97, 0xee, 0x73, 0xcb, 0x79, 0xee, 0x5a, 0xed, 0x76, 0xe7, 0xb4,
+	0xdd, 0x6c, 0x55, 0x73, 0xc8, 0x80, 0xeb, 0x73, 0x72, 0xbb, 0xf5, 0xfa, 0xb4, 0xe5, 0x74, 0xab,
+	0x79, 0x74, 0x0f, 0xee, 0xac, 0x92, 0xb8, 0x8d, 0xb7, 0xae, 0x73, 0xd2, 0xe9, 0xba, 0xed, 0xd3,
+	0xaf, 0x1b, 0x2d, 0xbb, 0x5a, 0x40, 0x7b, 0xb0, 0xbb, 0x40, 0x74, 0x5e, 0x75, 0xda, 0x4e, 0xab,
+	0x5a, 0x44, 0xff, 0x83, 0xc3, 0xa6, 0xfd, 0xd6, 0xe9, 0x5a, 0x27, 0x27, 0x2f, 0xbe, 0x6b, 0x3d,
+	0x75, 0x9d, 0xae, 0xd5, 0x6d, 0x2d, 0xf8, 0xb0, 0x26, 0x7d, 0x5c, 0xc1, 0x4a, 0x3c, 0xb9, 0x86,
+	0x0e, 0xe0, 0xdf, 0x2b, 0xe5, 0xfa, 0x98, 0x92, 0x34, 0x60, 0x35, 0xbb, 0x2f, 0xde, 0xb4, 0x56,
+	0x1e, 0xb0, 0x2e, 0x83, 0x9c, 0x93, 0x27, 0xa6, 0x37, 0xa4, 0xef, 0x0b, 0x12, 0x6d, 0x14, 0x7a,
+	0xd7, 0xd4, 0x4b, 0xf2, 0xc9, 0x9f, 0x01, 0x00, 0x00, 0xff, 0xff, 0xdc, 0x69, 0x3b, 0xfd, 0xf5,
+	0x0c, 0x00, 0x00,
 }
diff --git a/proto/beacon/p2p/v1/messages.proto b/proto/beacon/p2p/v1/messages.proto
index 11245e545b..ce391676dd 100644
--- a/proto/beacon/p2p/v1/messages.proto
+++ b/proto/beacon/p2p/v1/messages.proto
@@ -32,6 +32,7 @@ message BeaconBlockRequestBySlotNumber{
 
 message BeaconBlockResponse {
   BeaconBlock block = 1;
+  AggregatedAttestation attestation = 2;
 }
 
 message BeaconBlock {
@@ -42,7 +43,7 @@ message BeaconBlock {
   bytes active_state_hash = 5;
   bytes crystallized_state_hash = 6;
   google.protobuf.Timestamp timestamp = 7;
-  repeated AttestationRecord attestations = 8;
+  repeated AggregatedAttestation attestations = 8;
 }
 
 message CrystallizedStateHashAnnounce {
@@ -93,7 +94,7 @@ message ActiveStateResponse {
 }
 
 message ActiveState {
-  repeated AttestationRecord pending_attestations = 1;
+  repeated AggregatedAttestation pending_attestations = 1;
   repeated bytes recent_block_hashes = 2;
 }
 
@@ -107,7 +108,7 @@ message ValidatorRecord {
   uint64 end_dynasty = 7;
 }
 
-message AttestationRecord {
+message AggregatedAttestation {
   uint64 slot = 1;
   uint64 shard_id = 2;
   uint64 justified_slot = 3;
diff --git a/proto/beacon/rpc/v1/services.pb.go b/proto/beacon/rpc/v1/services.pb.go
index e25ec47560..edb21cf714 100644
--- a/proto/beacon/rpc/v1/services.pb.go
+++ b/proto/beacon/rpc/v1/services.pb.go
@@ -235,10 +235,10 @@ func (m *ProposeResponse) GetBlockHash() []byte {
 }
 
 type AttestRequest struct {
-	Attestation          *v1.AttestationRecord `protobuf:"bytes,1,opt,name=attestation,proto3" json:"attestation,omitempty"`
-	XXX_NoUnkeyedLiteral struct{}              `json:"-"`
-	XXX_unrecognized     []byte                `json:"-"`
-	XXX_sizecache        int32                 `json:"-"`
+	Attestation          *v1.AggregatedAttestation `protobuf:"bytes,1,opt,name=attestation,proto3" json:"attestation,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}                  `json:"-"`
+	XXX_unrecognized     []byte                    `json:"-"`
+	XXX_sizecache        int32                     `json:"-"`
 }
 
 func (m *AttestRequest) Reset()         { *m = AttestRequest{} }
@@ -265,7 +265,7 @@ func (m *AttestRequest) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_AttestRequest proto.InternalMessageInfo
 
-func (m *AttestRequest) GetAttestation() *v1.AttestationRecord {
+func (m *AttestRequest) GetAttestation() *v1.AggregatedAttestation {
 	if m != nil {
 		return m.Attestation
 	}
diff --git a/proto/beacon/rpc/v1/services.proto b/proto/beacon/rpc/v1/services.proto
index b4cc04042f..5864327be5 100644
--- a/proto/beacon/rpc/v1/services.proto
+++ b/proto/beacon/rpc/v1/services.proto
@@ -44,7 +44,7 @@ message ProposeResponse {
 }
 
 message AttestRequest {
-    ethereum.beacon.p2p.v1.AttestationRecord attestation = 1;
+    ethereum.beacon.p2p.v1.AggregatedAttestation attestation = 1;
 }
 
 message AttestResponse {
diff --git a/proto/testing/test.proto b/proto/testing/test.proto
index 73069570f5..3652a9e96e 100644
--- a/proto/testing/test.proto
+++ b/proto/testing/test.proto
@@ -10,4 +10,4 @@ message TestMessage {
 message Puzzle {
     string challenge = 1;
     string answer = 2;
-}
\ No newline at end of file
+}
diff --git a/validator/attester/service.go b/validator/attester/service.go
index 0aaa02f022..34662a675a 100644
--- a/validator/attester/service.go
+++ b/validator/attester/service.go
@@ -89,7 +89,7 @@ func (a *Attester) run(done <-chan struct{}, client pb.AttesterServiceClient) {
 			latestBlockHash := blake2b.Sum512(data)
 
 			req := &pb.AttestRequest{
-				Attestation: &pbp2p.AttestationRecord{
+				Attestation: &pbp2p.AggregatedAttestation{
 					Slot:             latestBeaconBlock.GetSlotNumber(),
 					ShardId:          a.shardID,
 					ShardBlockHash:   latestBlockHash[:],