diff --git a/TODO b/TODO
index 7e5e309a..54b34394 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,3 @@
-* Make Collection a Pseudo-array, a-la jQuery.
-
 * Hook up data binding in the view. Both ways. Parallel to models.
 
 * Add simple validations.
diff --git a/backbone.js b/backbone.js
index 350bbeed..babd2439 100644
--- a/backbone.js
+++ b/backbone.js
@@ -35,10 +35,11 @@
   // Backbone.Bindable
   // -----------------
 
-  // A module that can be mixed in to any object in order to provide it with
+  // A module that can be mixed in to *any object* in order to provide it with
   // custom events. You may `bind` or `unbind` a callback function to an event;
   // `trigger`-ing an event fires all callbacks in succession.
   //
+  //     var object = {};
   //     _.extend(object, Backbone.Bindable);
   //     object.bind('expand', function(){ alert('expanded'); });
   //     object.trigger('expand');
@@ -160,14 +161,26 @@
     // Set a hash of model attributes on the object, firing `changed` unless you
     // choose to silence it.
     set : function(attrs, options) {
+
+      // Extract attributes and options.
       options || (options = {});
       if (!attrs) return this;
       attrs = attrs._attributes || attrs;
       var now = this._attributes;
-      if ('id' in attrs) {
-        this.id = attrs.id;
-        if (this.collection) this.resource = this.collection.resource + '/' + this.id;
+
+      // Run validation if `validate` is defined.
+      if (this.validate) {
+        var error = this.validate(attrs);
+        if (error) {
+          this.trigger('error', error);
+          return false;
+        }
       }
+
+      // Check for changes of `id`.
+      if ('id' in attrs) this.id = attrs.id;
+
+      // Update attributes.
       for (var attr in attrs) {
         var val = attrs[attr];
         if (val === '') val = null;
@@ -179,6 +192,8 @@
           }
         }
       }
+
+      // Fire the `change` event, if the model has been changed.
       if (!options.silent && this._changed) this.change();
       return this;
     },
@@ -244,10 +259,10 @@
     save : function(attrs, options) {
       attrs   || (attrs = {});
       options || (options = {});
-      this.set(attrs, options);
+      if (!this.set(attrs, options)) return false;
       var model = this;
       var success = function(resp) {
-        model.set(resp.model);
+        if (!model.set(resp.model)) return false;
         if (options.success) options.success(model, resp);
       };
       var method = this.isNew() ? 'POST' : 'PUT';
@@ -420,7 +435,7 @@
       if (!(model instanceof Backbone.Model)) model = new this.model(model);
       model.collection = this;
       var success = function(model, resp) {
-        model.set(resp.model);
+        if (!model.set(resp.model)) return false;
         model.collection.add(model);
         if (options.success) options.success(model, resp);
       };
diff --git a/index.html b/index.html
index 165a4943..17cb08be 100644
--- a/index.html
+++ b/index.html
@@ -35,7 +35,7 @@
       ul.toc_section {
         font-size: 11px;
         line-height: 14px;
-        margin: 5px 0 20px 0;
+        margin: 5px 0 15px 0;
         padding-left: 0px;
         list-style-type: none;
         font-family: Lucida Grande;
diff --git a/test/model.js b/test/model.js
index 356a7a36..92b2e421 100644
--- a/test/model.js
+++ b/test/model.js
@@ -119,4 +119,23 @@ $(document).ready(function() {
     ok(_.isEqual(lastRequest[1], doc));
   });
 
-});
\ No newline at end of file
+  test("model: validate", function() {
+    var lastError;
+    var model = new Backbone.Model();
+    model.validate = function(attrs) {
+      if (attrs.admin) return "Can't change admin status.";
+    };
+    model.bind('error', function(error) {
+      lastError = error;
+    });
+    var result = model.set({a: 100});
+    equals(result, model);
+    equals(model.get('a'), 100);
+    equals(lastError, undefined);
+    result = model.set({a: 200, admin: true});
+    equals(result, false);
+    equals(model.get('a'), 100);
+    equals(lastError, "Can't change admin status.");
+  });
+
+});