diff --git a/packages/ui2/attrs.js b/packages/ui2/attrs.js
index 9b1df25584..ac5d77889f 100644
--- a/packages/ui2/attrs.js
+++ b/packages/ui2/attrs.js
@@ -1,3 +1,4 @@
+var UI = UI2;
 
 var ATTRIBUTE_NAME_REGEX = /^[^\s"'>/=/]+$/;
 
@@ -76,7 +77,8 @@ _extend(AttributeManager.prototype, {
     var handlers = self.handlers;
 
     component.autorun(function (c) {
-      if (component.stage !== Component.BUILT ||
+      if ((! component.isBuilt) ||
+          component.isDestroyed ||
           ! component.containsElement(element)) {
         c.stop();
         return;
diff --git a/packages/ui2/base.js b/packages/ui2/base.js
index a05717b31e..78759707fe 100644
--- a/packages/ui2/base.js
+++ b/packages/ui2/base.js
@@ -1,3 +1,13 @@
+// A very basic operation like Underscore's `_.extend` that
+// copies `src`'s own, enumerable properties onto `tgt` and
+// returns `tgt`.
+_extend = function (tgt, src) {
+  for (var k in src)
+    if (src.hasOwnProperty(k))
+      tgt[k] = src[k];
+  return tgt;
+};
+
 // @export UI2
 var UI = UI2 = {
   nextGuid: 2, // Component is 1!
@@ -14,78 +24,18 @@ var UI = UI2 = {
   // create instances (and the hope is we can gloss over the
   // difference in the docs).
 
-  Component: {
-    // If a Component has a `typeName` property set via `extend`,
-    // we make it use that name when printed in Chrome Dev Tools.
-    // If you then extend this Component and don't supply any
-    // new typeName, it should use the same typeName (or the
-    // most specific one in the case of an `extend` chain with
-    // `typeName` set at multiple points).
-    //
-    // To accomplish this, keeping performance in mind,
-    // any Component where `typeName` is explicitly set
-    // also has a function property `_constr` whose source-code
-    // name is `typeName`.  `extend` creates this `_constr`
-    // function, which can then be used internally as a
-    // constructor to quickly create new instances that
-    // pretty-print correctly.
-    typeName: "Component",
-    _constr: function Component() {},
+  Component: (function (constr) {
+    // Make sure the "class name" that Chrome infers for
+    // UI.Component is "Component", and that
+    // `new UI.Component._constr` (which is what `extend`
+    // does) also produces objects whose inferred class
+    // name is "Component".  Chrome's name inference rules
+    // are a little mysterious, but a function name in
+    // the source code (as in `function Component() {}`)
+    // seems to be reliable and high precedence.
+    return _extend(new constr, {_constr: constr});
+  })(function Component() {}),
 
-    _super: null,
-    guid: 1,
-
-    extend: function (props) {
-      // this function should never cause `props` to be
-      // mutated in case people want to reuse `props` objects
-      // in a mixin-like way.
-
-      if (this.isInited)
-        // Disallow extending inited Components so that
-        // inited Components don't inherit instance-specific
-        // properties from other inited Components, just
-        // default values.
-        throw new Error("Can't extend an inited Component");
-
-      // Any Component with a typeName of "Foo" (say) is given
-      // a `._constr` of the form `function Foo() {}`.
-      if (props && props.typeName)
-        this._constr =
-          Function("return function " +
-                   sanitizeTypeName(props.typeName) +
-                   "() {};")();
-
-      // We don't know where we're getting `_constr` from --
-      // it might be from some supertype -- just that it has
-      // the right function name.  So set the `prototype`
-      // property each time we use it as a constructor.
-      this._constr.prototype = this;
-
-      var c = new this._constr;
-      if (props)
-        _extend(c, props);
-
-      // for efficient Component instantiations, we assign
-      // as few things as possible here.
-      c._super = this;
-      c.guid = UI.nextGuid++;
-
-      return c;
-    },
-
-    // `x.isa(Foo)` where `x` is a Component returns `true`
-    // if `x` is `Foo` or a Component that descends from
-    // (transitively extends) `Foo`.
-    isa: function (obj) {
-      var x = this;
-      while (x) {
-        if (x === obj)
-          return true;
-        x = x._super;
-      }
-      return false;
-    }
-  },
   isComponent: function (obj) {
     return obj && obj.isa === UI.Component.isa;
   },
@@ -102,15 +52,86 @@ var UI = UI2 = {
   }
 };
 
-// A very basic operation like Underscore's `_.extend` that
-// copies `src`'s own, enumerable properties onto `tgt` and
-// returns `tgt`.
-_extend = function (tgt, src) {
-  for (var k in src)
-    if (src.hasOwnProperty(k))
-      tgt[k] = src[k];
-  return tgt;
-};
+_extend(UI.Component, {
+  // If a Component has a `typeName` property set via `extend`,
+  // we make it use that name when printed in Chrome Dev Tools.
+  // If you then extend this Component and don't supply any
+  // new typeName, it should use the same typeName (or the
+  // most specific one in the case of an `extend` chain with
+  // `typeName` set at multiple points).
+  //
+  // To accomplish this, keeping performance in mind,
+  // any Component where `typeName` is explicitly set
+  // also has a function property `_constr` whose source-code
+  // name is `typeName`.  `extend` creates this `_constr`
+  // function, which can then be used internally as a
+  // constructor to quickly create new instances that
+  // pretty-print correctly.
+  typeName: "Component",
+  _constr: function Component() {},
+
+  _super: null,
+  guid: 1,
+
+  extend: function (props) {
+    // this function should never cause `props` to be
+    // mutated in case people want to reuse `props` objects
+    // in a mixin-like way.
+
+    if (this.isInited)
+      // Disallow extending inited Components so that
+      // inited Components don't inherit instance-specific
+      // properties from other inited Components, just
+      // default values.
+      throw new Error("Can't extend an inited Component");
+
+    var constr;
+    var constrMade = false;
+    // Any Component with a typeName of "Foo" (say) is given
+    // a `._constr` of the form `function Foo() {}`.
+    if (props && props.typeName) {
+      constr = Function("return function " +
+                        sanitizeTypeName(props.typeName) +
+                        "() {};")();
+      constrMade = true;
+    } else {
+      constr = this._constr;
+    }
+
+    // We don't know where we're getting `constr` from --
+    // it might be from some supertype -- just that it has
+    // the right function name.  So set the `prototype`
+    // property each time we use it as a constructor.
+    constr.prototype = this;
+
+    var c = new constr;
+    if (constrMade)
+      c._constr = constr;
+
+    if (props)
+      _extend(c, props);
+
+    // for efficient Component instantiations, we assign
+    // as few things as possible here.
+    c._super = this;
+    c.guid = UI.nextGuid++;
+
+    return c;
+  },
+
+  // `x.isa(Foo)` where `x` is a Component returns `true`
+  // if `x` is `Foo` or a Component that descends from
+  // (transitively extends) `Foo`.
+  isa: function (obj) {
+    var x = this;
+    while (x) {
+      if (x === obj)
+        return true;
+      x = x._super;
+    }
+    return false;
+  }
+});
 
 callChainedCallback = function (comp, propName) {
   if (comp._super)
@@ -532,7 +553,6 @@ _extend(UI.Component, {
   _attach: function (parentNode, beforeNode) {
     var self = this;
 
-    this._requireBuilt();
     this._requireNotDestroyed();
 
     if (! self.isInited)
diff --git a/packages/ui2/components.js b/packages/ui2/components.js
index 8bfaa68cf4..75be5b3202 100644
--- a/packages/ui2/components.js
+++ b/packages/ui2/components.js
@@ -1,8 +1,5 @@
-
-// All `<body>` tags in HTML files are compiled to extend
-// Body.  If you put helpers and events on Body, they all
-// inherit them.
-UI.Body = Component.extend({isRoot: true});
+var UI = UI2;
+var Component = UI.Component;
 
 UI.Text = Component.extend({
   typeName: 'Text',
@@ -11,8 +8,8 @@ UI.Text = Component.extend({
     return String(x == null ? '' : x);
   },
   render: function (buf) {
-    var data = this.data();
-    buf(this._encodeEntities(this._stringify(data)));
+    var data = this.get();
+    buf.write(this._encodeEntities(this._stringify(data)));
   }
 });
 
@@ -22,11 +19,11 @@ UI.HTML = Component.extend({
     return String(x == null ? '' : x);
   },
   render: function (buf) {
-    var data = this.data();
-    buf(this._stringify(data));
+    var data = this.get();
+    buf.write(this._stringify(data));
   }
 });
-
+/*
 UI.If = Component.extend({
   typeName: 'If',
   init: function () {
@@ -89,4 +86,5 @@ UI.Counter = Component.extend({
       self.increment();
     });
   }
-});
\ No newline at end of file
+});
+ */
\ No newline at end of file
diff --git a/packages/ui2/fields.js b/packages/ui2/fields.js
new file mode 100644
index 0000000000..52811afe39
--- /dev/null
+++ b/packages/ui2/fields.js
@@ -0,0 +1,14 @@
+var UI = UI2;
+
+_extend(UI.Component, {
+  get: function (id) {
+    // this is the (! id) case where `id` is `""` or absent.
+    // actually it should probably search up the parent tree too.
+    return (typeof this.data === 'function' ?
+            this.data() : this.data);
+  },
+  // convenient syntax
+  withData: function (data) {
+    return this.extend({data: data});
+  }
+});
diff --git a/packages/ui2/package.js b/packages/ui2/package.js
index 0b1bde845e..57af12f042 100644
--- a/packages/ui2/package.js
+++ b/packages/ui2/package.js
@@ -8,7 +8,11 @@ Package.on_use(function (api) {
   api.use('ejson');
   api.use('ordered-dict');
 
-  api.add_files(['base.js']);
+  api.add_files(['base.js',
+                 'attrs.js',
+                 'render.js',
+                 'fields.js',
+                 'components.js']);
 });
 
 Package.on_test(function (api) {
@@ -17,6 +21,7 @@ Package.on_test(function (api) {
   api.use(['test-helpers', 'underscore'], 'client');
 
   api.add_files([
-    'base_tests.js'
+    'base_tests.js',
+    'render_tests.js'
   ], 'client');
 });
diff --git a/packages/ui2/render.js b/packages/ui2/render.js
index 342e44f4d5..4a21bafa44 100644
--- a/packages/ui2/render.js
+++ b/packages/ui2/render.js
@@ -97,7 +97,7 @@ makeRenderBuffer = function (component, options) {
       componentsToAttach[commentString] = arg;
     } else if (arg.extend) {
       // `{extend: componentOrFunction, props: object}`
-      if (UI.isComponent(arg.extend)) {
+      /*      if (UI.isComponent(arg.extend)) {
         // In `{extend: comp}` with no `props`, it's ok
         // for `comp` to be already inited.  This lets
         // you write `{{> foo}}` to insert already-inited
@@ -133,8 +133,8 @@ makeRenderBuffer = function (component, options) {
         var curChild = curType.create(arg.args);
         handle(curChild);
       } else {
-        throw new Error("Expected 'type' to be Component or function");
-      }
+        throw new Error("Expected 'extend' to be Component or function");
+      }*/
     } else if (arg.attrs) {
       // `{attrs: functionOrDictionary }`
       // attrs object inserts zero or more `name="value"` items
@@ -175,7 +175,8 @@ makeRenderBuffer = function (component, options) {
     }
   };
 
-  var buf = function (/*args*/) {
+  var buf = {};
+  buf.write = function (/*args*/) {
     for (var i = 0; i < arguments.length; i++)
       handle(arguments[i]);
   };
@@ -204,13 +205,13 @@ makeRenderBuffer = function (component, options) {
                 if (n === root.lastChild)
                   end = comp;
               }
-              if (comp.stage === Component.INITIAL) {
+              if (! comp.isInited) {
                 component.add(comp);
               } else if (comp.parent !== component) {
                 throw new Error("Component used in render must be a child " +
                                 "(or addable as one)");
               }
-              comp.attach(parent, n);
+              comp._attach(parent, n);
               parent.removeChild(n);
               delete componentsToAttach[n.nodeValue];
             }
diff --git a/packages/ui2/render_tests.js b/packages/ui2/render_tests.js
new file mode 100644
index 0000000000..d665baef83
--- /dev/null
+++ b/packages/ui2/render_tests.js
@@ -0,0 +1,66 @@
+var UI = UI2;
+
+Tinytest.add("ui - render", function (test) {
+  var c, R;
+
+  c = UI.Component.extend({
+    render: function (buf) {
+      buf.write("asdf");
+    }
+  });
+
+  c.build();
+  test.equal($(c._offscreen).html(), "asdf");
+  c.destroy();
+
+
+
+  c = UI.Component.extend({
+    render: function (buf) {
+      buf.write("<div>asdf</div>");
+    }
+  });
+
+  c.build();
+  test.equal($(c._offscreen).html(), "<div>asdf</div>");
+  c.destroy();
+
+
+
+  R = ReactiveVar("blam");
+  c = UI.Component.extend({
+    render: function (buf) {
+      buf.write(
+        "foo",
+        UI.Text.withData(function () { return R.get(); }),
+        "bar");
+    }
+  });
+
+  c.build();
+  test.equal($(c._offscreen).html(), "fooblambar");
+  R.set("ki");
+  Deps.flush();
+  test.equal($(c._offscreen).html(), "fookibar");
+  c.destroy();
+
+
+
+  R = ReactiveVar("<hr>");
+  c = UI.Component.extend({
+    render: function (buf) {
+      buf.write(
+        "foo",
+        UI.HTML.withData(function () { return R.get(); }),
+        "bar");
+    }
+  });
+
+  c.build();
+  test.equal($(c._offscreen).html(), "foo<hr>bar");
+  R.set("<div>hi</div>");
+  Deps.flush();
+  test.equal($(c._offscreen).html(), "foo<div>hi</div>bar");
+  c.destroy();
+
+});
\ No newline at end of file