diff --git a/src/renderers/dom/client/ReactDOMComponentTree.js b/src/renderers/dom/client/ReactDOMComponentTree.js
index dfd128ac2e..53d29d2dca 100644
--- a/src/renderers/dom/client/ReactDOMComponentTree.js
+++ b/src/renderers/dom/client/ReactDOMComponentTree.js
@@ -77,7 +77,7 @@ function precacheChildNodes(inst, node) {
       continue;
     }
     var childInst = children[name];
-    var childID = childInst._rootNodeID;
+    var childID = getRenderedNativeOrTextFromComponent(childInst)._domID;
     if (childID == null) {
       // We're currently unmounting this child in ReactMultiChild; skip it.
       continue;
@@ -85,7 +85,7 @@ function precacheChildNodes(inst, node) {
     // We assume the child nodes are in the same order as the child instances.
     for (; childNode !== null; childNode = childNode.nextSibling) {
       if (childNode.nodeType === 1 &&
-          childNode.getAttribute(ATTR_NAME) === childID) {
+          childNode.getAttribute(ATTR_NAME) === String(childID)) {
         precacheNode(childInst, childNode);
         continue outer;
       }
diff --git a/src/renderers/dom/client/ReactMount.js b/src/renderers/dom/client/ReactMount.js
index 88ed3a01a8..4db71492bb 100644
--- a/src/renderers/dom/client/ReactMount.js
+++ b/src/renderers/dom/client/ReactMount.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var ClientReactRootIndex = require('ClientReactRootIndex');
 var DOMLazyTree = require('DOMLazyTree');
 var DOMProperty = require('DOMProperty');
 var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
@@ -20,7 +19,6 @@ var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactDOMContainerInfo = require('ReactDOMContainerInfo');
 var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
 var ReactElement = require('ReactElement');
-var ReactInstanceHandles = require('ReactInstanceHandles');
 var ReactMarkupChecksum = require('ReactMarkupChecksum');
 var ReactPerf = require('ReactPerf');
 var ReactReconciler = require('ReactReconciler');
@@ -35,23 +33,12 @@ var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
 var warning = require('warning');
 
 var ATTR_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
+var ROOT_ATTR_NAME = DOMProperty.ROOT_ATTRIBUTE_NAME;
 
 var ELEMENT_NODE_TYPE = 1;
 var DOC_NODE_TYPE = 9;
 var DOCUMENT_FRAGMENT_NODE_TYPE = 11;
 
-
-/** Mapping from reactRootID to React component instance. */
-var instancesByReactRootID = {};
-
-/** Mapping from reactRootID to `container` nodes. */
-var containersByReactRootID = {};
-
-if (__DEV__) {
-  /** __DEV__-only mapping from reactRootID to root elements. */
-  var rootElementsByReactRootID = {};
-}
-
 /**
  * Finds the index of the first character
  * that's not common between the two given strings.
@@ -85,20 +72,11 @@ function getReactRootElementInContainer(container) {
   }
 }
 
-/**
- * @param {DOMElement} container DOM element that may contain a React component.
- * @return {?string} A "reactRoot" ID, if a React component is rendered.
- */
-function getReactRootID(container) {
-  var rootElement = getReactRootElementInContainer(container);
-  return rootElement && internalGetID(rootElement);
-}
-
 function internalGetID(node) {
   // If node is something like a window, document, or text node, none of
   // which support attributes or a .getAttribute method, gracefully return
   // the empty string, as if the attribute were missing.
-  return node && node.getAttribute && node.getAttribute(ATTR_NAME) || '';
+  return node.getAttribute && node.getAttribute(ATTR_NAME) || '';
 }
 
 /**
@@ -111,7 +89,7 @@ function internalGetID(node) {
  * @param {boolean} shouldReuseMarkup If true, do not insert markup
  */
 function mountComponentIntoNode(
-  componentInstance,
+  wrapperInstance,
   rootID,
   container,
   transaction,
@@ -119,18 +97,18 @@ function mountComponentIntoNode(
   context
 ) {
   var markup = ReactReconciler.mountComponent(
-    componentInstance,
+    wrapperInstance,
     rootID,
     transaction,
     null,
-    ReactDOMContainerInfo(container),
+    ReactDOMContainerInfo(wrapperInstance, container),
     context
   );
-  componentInstance._renderedComponent._topLevelWrapper = componentInstance;
+  wrapperInstance._renderedComponent._topLevelWrapper = wrapperInstance;
   ReactMount._mountImageIntoNode(
     markup,
     container,
-    componentInstance,
+    wrapperInstance,
     shouldReuseMarkup,
     transaction
   );
@@ -200,10 +178,21 @@ function unmountComponentFromNode(instance, container) {
  * rendered by React but is not a root element.
  * @internal
  */
-function hasNonRootReactChild(node) {
-  var reactRootID = getReactRootID(node);
-  return reactRootID ? reactRootID !==
-    ReactInstanceHandles.getReactRootIDFromNodeID(reactRootID) : false;
+function hasNonRootReactChild(container) {
+  var rootElement = getReactRootElementInContainer(container);
+  return !!(
+    rootElement &&
+    internalGetID(rootElement) &&
+    !rootElement.hasAttribute(ROOT_ATTR_NAME)
+  );
+}
+
+function getTopLevelWrapperInContainer(container) {
+  var rootEl = getReactRootElementInContainer(container);
+  var prevNativeInstance =
+    rootEl && ReactDOMComponentTree.getInstanceFromNode(rootEl);
+  return !prevNativeInstance || prevNativeInstance._nativeParent ? null :
+    prevNativeInstance._nativeContainerInfo._topLevelWrapper;
 }
 
 /**
@@ -243,9 +232,6 @@ var ReactMount = {
 
   TopLevelWrapper: TopLevelWrapper,
 
-  /** Exposed for debugging purposes **/
-  _instancesByReactRootID: instancesByReactRootID,
-
   /**
    * This is a hook provided to support rendering React components while
    * ensuring that the apparent scroll position of its `container` does not
@@ -277,39 +263,9 @@ var ReactMount = {
       }
     });
 
-    if (__DEV__) {
-      // Record the root element in case it later gets transplanted.
-      rootElementsByReactRootID[getReactRootID(container)] =
-        getReactRootElementInContainer(container);
-    }
-
     return prevComponent;
   },
 
-  /**
-   * Register a component into the instance map and starts scroll value
-   * monitoring
-   * @param {ReactComponent} nextComponent component instance to render
-   * @param {DOMElement} container container to render into
-   * @return {string} reactRoot ID prefix
-   */
-  _registerComponent: function(nextComponent, container) {
-    invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
-      '_registerComponent(...): Target container is not a DOM element.'
-    );
-
-    ReactBrowserEventEmitter.ensureScrollValueMonitoring();
-
-    var reactRootID = ReactMount.registerContainer(container);
-    instancesByReactRootID[reactRootID] = nextComponent;
-    return reactRootID;
-  },
-
   /**
    * Render a new component into the DOM.
    * @param {ReactElement} nextElement element to render
@@ -336,12 +292,18 @@ var ReactMount = {
         'ReactCompositeComponent'
     );
 
-    var componentInstance = instantiateReactComponent(nextElement, null);
-    var reactRootID = ReactMount._registerComponent(
-      componentInstance,
-      container
+    invariant(
+      container && (
+        container.nodeType === ELEMENT_NODE_TYPE ||
+        container.nodeType === DOC_NODE_TYPE ||
+        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
+      ),
+      '_registerComponent(...): Target container is not a DOM element.'
     );
 
+    ReactBrowserEventEmitter.ensureScrollValueMonitoring();
+    var componentInstance = instantiateReactComponent(nextElement, null);
+
     // The initial render is synchronous but any updates that happen during
     // rendering, in componentWillMount or componentDidMount, will be batched
     // according to the current batching strategy.
@@ -349,18 +311,12 @@ var ReactMount = {
     ReactUpdates.batchedUpdates(
       batchedMountComponentIntoNode,
       componentInstance,
-      reactRootID,
+      '',
       container,
       shouldReuseMarkup,
       context
     );
 
-    if (__DEV__) {
-      // Record the root element in case it later gets transplanted.
-      rootElementsByReactRootID[reactRootID] =
-        getReactRootElementInContainer(container);
-    }
-
     return componentInstance;
   },
 
@@ -429,7 +385,7 @@ var ReactMount = {
       nextElement
     );
 
-    var prevComponent = instancesByReactRootID[getReactRootID(container)];
+    var prevComponent = getTopLevelWrapperInContainer(container);
 
     if (prevComponent) {
       var prevWrappedElement = prevComponent._currentElement;
@@ -519,27 +475,6 @@ var ReactMount = {
     return ReactMount._renderSubtreeIntoContainer(null, nextElement, container, callback);
   },
 
-  /**
-   * Registers a container node into which React components will be rendered.
-   * This also creates the "reactRoot" ID that will be assigned to the element
-   * rendered within.
-   *
-   * @param {DOMElement} container DOM element to register as a container.
-   * @return {string} The "reactRoot" ID of elements rendered within.
-   */
-  registerContainer: function(container) {
-    var id = getReactRootID(container);
-    // If one exists, make sure it is a valid "reactRoot" ID.
-    if (!id || id !== ReactInstanceHandles.getReactRootIDFromNodeID(id)) {
-      // No valid "reactRoot" ID found, create one.
-      id = ReactInstanceHandles.createReactRootID(
-        ClientReactRootIndex.createReactRootIndex()
-      );
-    }
-    containersByReactRootID[id] = container;
-    return id;
-  },
-
   /**
    * Unmounts and destroys the React component rendered in the `container`.
    *
@@ -571,19 +506,15 @@ var ReactMount = {
       'unmountComponentAtNode(...): Target container is not a DOM element.'
     );
 
-    var reactRootID = getReactRootID(container);
-    var component = instancesByReactRootID[reactRootID];
-    if (!component) {
+    var prevComponent = getTopLevelWrapperInContainer(container);
+    if (!prevComponent) {
       // Check if the node being unmounted was rendered by React, but isn't a
       // root node.
       var containerHasNonRootReactChild = hasNonRootReactChild(container);
 
       // Check if the container itself is a React root node.
-      var containerID = internalGetID(container);
       var isContainerReactRoot =
-          containerID &&
-          containerID ===
-            ReactInstanceHandles.getReactRootIDFromNodeID(containerID);
+        container.nodeType === 1 && container.hasAttribute(ROOT_ATTR_NAME);
 
       if (__DEV__) {
         warning(
@@ -604,14 +535,9 @@ var ReactMount = {
     }
     ReactUpdates.batchedUpdates(
       unmountComponentFromNode,
-      component,
+      prevComponent,
       container
     );
-    delete instancesByReactRootID[reactRootID];
-    delete containersByReactRootID[reactRootID];
-    if (__DEV__) {
-      delete rootElementsByReactRootID[reactRootID];
-    }
     return true;
   },
 
diff --git a/src/renderers/dom/client/__tests__/ReactRenderDocument-test.js b/src/renderers/dom/client/__tests__/ReactRenderDocument-test.js
index 02230bf46b..6ba359b628 100644
--- a/src/renderers/dom/client/__tests__/ReactRenderDocument-test.js
+++ b/src/renderers/dom/client/__tests__/ReactRenderDocument-test.js
@@ -33,14 +33,6 @@ describe('rendering React components at document', function() {
   beforeEach(function() {
     jest.resetModuleRegistry();
 
-    // Negative integer creator. So they won't get confused with
-    // the Client positive ids.
-    var ServerReactRootIndex = require('ServerReactRootIndex');
-    var serverId = -1;
-    ServerReactRootIndex.createReactRootIndex.mockImplementation(function() {
-      return serverId--;
-    });
-
     React = require('React');
     ReactDOM = require('ReactDOM');
     ReactDOMServer = require('ReactDOMServer');
@@ -221,8 +213,8 @@ describe('rendering React components at document', function() {
       'quirks by rendering at the document root. You should look for ' +
       'environment dependent code in your components and ensure ' +
       'the props are the same client and server side:\n' +
-      ' (client) ata-reactid=".-1.1">Hello world</body></\n' +
-      ' (server) ata-reactid=".-1.1">Goodbye world</body>'
+      ' (client) dy data-reactid="4">Hello world</body></\n' +
+      ' (server) dy data-reactid="4">Goodbye world</body>'
     );
   });
 
diff --git a/src/renderers/dom/server/ReactServerRendering.js b/src/renderers/dom/server/ReactServerRendering.js
index ec543920c7..ffec7fcdf5 100644
--- a/src/renderers/dom/server/ReactServerRendering.js
+++ b/src/renderers/dom/server/ReactServerRendering.js
@@ -11,15 +11,14 @@
  */
 'use strict';
 
+var ReactDOMContainerInfo = require('ReactDOMContainerInfo');
 var ReactDefaultBatchingStrategy = require('ReactDefaultBatchingStrategy');
 var ReactElement = require('ReactElement');
-var ReactInstanceHandles = require('ReactInstanceHandles');
 var ReactMarkupChecksum = require('ReactMarkupChecksum');
 var ReactServerBatchingStrategy = require('ReactServerBatchingStrategy');
 var ReactServerRenderingTransaction =
   require('ReactServerRenderingTransaction');
 var ReactUpdates = require('ReactUpdates');
-var ServerReactRootIndex = require('ServerReactRootIndex');
 
 var emptyObject = require('emptyObject');
 var instantiateReactComponent = require('instantiateReactComponent');
@@ -39,18 +38,15 @@ function renderToStringImpl(element, makeStaticMarkup) {
   try {
     ReactUpdates.injection.injectBatchingStrategy(ReactServerBatchingStrategy);
 
-    var id = ReactInstanceHandles.createReactRootID(
-      ServerReactRootIndex.createReactRootIndex()
-    );
     transaction = ReactServerRenderingTransaction.getPooled(makeStaticMarkup);
 
     return transaction.perform(function() {
       var componentInstance = instantiateReactComponent(element, null);
       var markup = componentInstance.mountComponent(
-        id,
+        '',
         transaction,
         null,
-        null,
+        ReactDOMContainerInfo(),
         emptyObject
       );
       if (!makeStaticMarkup) {
diff --git a/src/renderers/dom/server/__tests__/ReactServerRendering-test.js b/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
index 83c54a8741..2462d7e853 100644
--- a/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
+++ b/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
@@ -20,6 +20,7 @@ var ReactTestUtils;
 var ReactServerRendering;
 
 var ID_ATTRIBUTE_NAME;
+var ROOT_ATTRIBUTE_NAME;
 
 describe('ReactServerRendering', function() {
   beforeEach(function() {
@@ -36,7 +37,7 @@ describe('ReactServerRendering', function() {
 
     var DOMProperty = require('DOMProperty');
     ID_ATTRIBUTE_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
-    spyOn(console, 'error');
+    ROOT_ATTRIBUTE_NAME = DOMProperty.ROOT_ATTRIBUTE_NAME;
   });
 
   describe('renderToString', function() {
@@ -45,7 +46,8 @@ describe('ReactServerRendering', function() {
         <span>hello world</span>
       );
       expect(response).toMatch(
-        '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+" ' +
+        '<span ' + ROOT_ATTRIBUTE_NAME + '="" ' +
+          ID_ATTRIBUTE_NAME + '="[^"]+" ' +
           ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+">hello world</span>'
       );
     });
@@ -55,7 +57,8 @@ describe('ReactServerRendering', function() {
         <img />
       );
       expect(response).toMatch(
-        '<img ' + ID_ATTRIBUTE_NAME + '="[^"]+" ' +
+        '<img ' + ROOT_ATTRIBUTE_NAME + '="" ' +
+          ID_ATTRIBUTE_NAME + '="[^"]+" ' +
           ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"/>'
       );
     });
@@ -65,7 +68,8 @@ describe('ReactServerRendering', function() {
         <img data-attr=">" />
       );
       expect(response).toMatch(
-        '<img data-attr="&gt;" ' + ID_ATTRIBUTE_NAME + '="[^"]+" ' +
+        '<img data-attr="&gt;" ' + ROOT_ATTRIBUTE_NAME + '="" ' +
+          ID_ATTRIBUTE_NAME + '="[^"]+" ' +
           ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+"/>'
       );
     });
@@ -95,7 +99,8 @@ describe('ReactServerRendering', function() {
         <Parent />
       );
       expect(response).toMatch(
-        '<div ' + ID_ATTRIBUTE_NAME + '="[^"]+" ' +
+        '<div ' + ROOT_ATTRIBUTE_NAME + '="" ' +
+          ID_ATTRIBUTE_NAME + '="[^"]+" ' +
           ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+">' +
           '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+">' +
             '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+">My name is </span>' +
@@ -145,7 +150,8 @@ describe('ReactServerRendering', function() {
         );
 
         expect(response).toMatch(
-          '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+" ' +
+          '<span ' + ROOT_ATTRIBUTE_NAME + '="" ' +
+            ID_ATTRIBUTE_NAME + '="[^"]+" ' +
             ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="[^"]+">' +
             '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+">Component name: </span>' +
             '<span ' + ID_ATTRIBUTE_NAME + '="[^"]+">TestComponent</span>' +
@@ -225,6 +231,7 @@ describe('ReactServerRendering', function() {
       // Now simulate a situation where the app is not idempotent. React should
       // warn but do the right thing.
       element.innerHTML = lastMarkup;
+      spyOn(console, 'error');
       var instance = ReactDOM.render(<TestComponent name="y" />, element);
       expect(mountCount).toEqual(4);
       expect(console.error.argsForCall.length).toBe(1);
diff --git a/src/renderers/dom/shared/DOMProperty.js b/src/renderers/dom/shared/DOMProperty.js
index 69c18dd56e..2da8d2d651 100644
--- a/src/renderers/dom/shared/DOMProperty.js
+++ b/src/renderers/dom/shared/DOMProperty.js
@@ -167,6 +167,7 @@ var defaultValueCache = {};
 var DOMProperty = {
 
   ID_ATTRIBUTE_NAME: 'data-reactid',
+  ROOT_ATTRIBUTE_NAME: 'data-reactroot',
 
   /**
    * Map from property "standard name" to an object with info about how to set
diff --git a/src/renderers/dom/shared/DOMPropertyOperations.js b/src/renderers/dom/shared/DOMPropertyOperations.js
index 00aa1a5e56..092ea8af2b 100644
--- a/src/renderers/dom/shared/DOMPropertyOperations.js
+++ b/src/renderers/dom/shared/DOMPropertyOperations.js
@@ -125,6 +125,14 @@ var DOMPropertyOperations = {
     node.setAttribute(DOMProperty.ID_ATTRIBUTE_NAME, id);
   },
 
+  createMarkupForRoot: function() {
+    return DOMProperty.ROOT_ATTRIBUTE_NAME + '=""';
+  },
+
+  setAttributeForRoot: function(node) {
+    node.setAttribute(DOMProperty.ROOT_ATTRIBUTE_NAME, '');
+  },
+
   /**
    * Creates markup for a property.
    *
diff --git a/src/renderers/dom/shared/ReactDOMComponent.js b/src/renderers/dom/shared/ReactDOMComponent.js
index 73b06e3c05..27ed5b6767 100644
--- a/src/renderers/dom/shared/ReactDOMComponent.js
+++ b/src/renderers/dom/shared/ReactDOMComponent.js
@@ -301,11 +301,11 @@ function enqueuePutListener(inst, registrationName, listener, transaction) {
     );
   }
   var containerInfo = inst._nativeContainerInfo;
-  if (!containerInfo) {
+  var doc = containerInfo._ownerDocument;
+  if (!doc) {
     // Server rendering.
     return;
   }
-  var doc = containerInfo._ownerDocument;
   listenTo(registrationName, doc);
   transaction.getReactMountReady().enqueue(putListener, {
     inst: inst,
@@ -494,6 +494,8 @@ function isCustomComponent(tagName, props) {
   return tagName.indexOf('-') >= 0 || props.is != null;
 }
 
+var globalIdCounter = 1;
+
 /**
  * Creates a new React class that is idempotent and capable of containing other
  * React components. It accepts event listeners and DOM properties that are
@@ -518,6 +520,7 @@ function ReactDOMComponent(tag) {
   this._nativeNode = null;
   this._nativeParent = null;
   this._rootNodeID = null;
+  this._domID = null;
   this._nativeContainerInfo = null;
   this._wrapperState = null;
   this._topLevelWrapper = null;
@@ -554,7 +557,8 @@ ReactDOMComponent.Mixin = {
     nativeContainerInfo,
     context
   ) {
-    this._rootNodeID = rootID;
+    this._rootNodeID = globalIdCounter++;
+    this._domID = nativeContainerInfo._idCounter++;
     this._nativeParent = nativeParent;
     this._nativeContainerInfo = nativeContainerInfo;
 
@@ -604,7 +608,7 @@ ReactDOMComponent.Mixin = {
     if (nativeParent != null) {
       namespaceURI = nativeParent._namespaceURI;
       parentTag = nativeParent._tag;
-    } else if (nativeContainerInfo != null) {
+    } else if (nativeContainerInfo._tag) {
       namespaceURI = nativeContainerInfo._namespaceURI;
       parentTag = nativeContainerInfo._tag;
     }
@@ -625,7 +629,7 @@ ReactDOMComponent.Mixin = {
       var parentInfo;
       if (nativeParent != null) {
         parentInfo = nativeParent._ancestorInfo;
-      } else if (nativeContainerInfo != null) {
+      } else if (nativeContainerInfo._tag) {
         parentInfo = nativeContainerInfo._ancestorInfo;
       }
       if (parentInfo) {
@@ -660,7 +664,10 @@ ReactDOMComponent.Mixin = {
       }
       ReactDOMComponentTree.precacheNode(this, el);
       this._flags |= Flags.hasCachedChildNodes;
-      DOMPropertyOperations.setAttributeForID(el, this._rootNodeID);
+      if (!this._nativeParent) {
+        DOMPropertyOperations.setAttributeForRoot(el);
+      }
+      DOMPropertyOperations.setAttributeForID(el, this._domID);
       this._updateDOMProperties(null, props, transaction);
       var lazyTree = DOMLazyTree(el);
       this._createInitialChildren(transaction, props, context, lazyTree);
@@ -757,8 +764,11 @@ ReactDOMComponent.Mixin = {
       return ret;
     }
 
-    var markupForID = DOMPropertyOperations.createMarkupForID(this._rootNodeID);
-    return ret + ' ' + markupForID;
+    if (!this._nativeParent) {
+      ret += ' ' + DOMPropertyOperations.createMarkupForRoot();
+    }
+    ret += ' ' + DOMPropertyOperations.createMarkupForID(this._domID);
+    return ret;
   },
 
   /**
@@ -1145,6 +1155,7 @@ ReactDOMComponent.Mixin = {
     EventPluginHub.deleteAllListeners(this);
     ReactComponentBrowserEnvironment.unmountIDFromEnvironment(this._rootNodeID);
     this._rootNodeID = null;
+    this._domID = null;
     this._wrapperState = null;
   },
 
diff --git a/src/renderers/dom/shared/ReactDOMContainerInfo.js b/src/renderers/dom/shared/ReactDOMContainerInfo.js
index cbee0b5e7d..f0b97c037f 100644
--- a/src/renderers/dom/shared/ReactDOMContainerInfo.js
+++ b/src/renderers/dom/shared/ReactDOMContainerInfo.js
@@ -15,15 +15,19 @@ var validateDOMNesting = require('validateDOMNesting');
 
 var DOC_NODE_TYPE = 9;
 
-function ReactDOMContainerInfo(node) {
+function ReactDOMContainerInfo(topLevelWrapper, node) {
   var info = {
-    _ownerDocument: node.nodeType === DOC_NODE_TYPE ? node : node.ownerDocument,
-    _tag: node.nodeName.toLowerCase(),
-    _namespaceURI: node.namespaceURI,
+    _topLevelWrapper: topLevelWrapper,
+    _idCounter: 1,
+    _ownerDocument: node ?
+      node.nodeType === DOC_NODE_TYPE ? node : node.ownerDocument :
+      null,
+    _tag: node ? node.nodeName.toLowerCase() : null,
+    _namespaceURI: node ? node.namespaceURI : null,
   };
   if (__DEV__) {
-    info._ancestorInfo =
-      validateDOMNesting.updatedAncestorInfo(null, info._tag, null);
+    info._ancestorInfo = node ?
+      validateDOMNesting.updatedAncestorInfo(null, info._tag, null) : null;
   }
   return info;
 }
diff --git a/src/renderers/dom/shared/ReactDOMTextComponent.js b/src/renderers/dom/shared/ReactDOMTextComponent.js
index 7404b61f37..4ffa9c4746 100644
--- a/src/renderers/dom/shared/ReactDOMTextComponent.js
+++ b/src/renderers/dom/shared/ReactDOMTextComponent.js
@@ -15,8 +15,6 @@
 var DOMChildrenOperations = require('DOMChildrenOperations');
 var DOMLazyTree = require('DOMLazyTree');
 var DOMPropertyOperations = require('DOMPropertyOperations');
-var ReactComponentBrowserEnvironment =
-  require('ReactComponentBrowserEnvironment');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactPerf = require('ReactPerf');
 
@@ -60,7 +58,7 @@ assign(ReactDOMTextComponent.prototype, {
     this._nativeParent = null;
 
     // Properties
-    this._rootNodeID = null;
+    this._domID = null;
     this._mountIndex = 0;
   },
 
@@ -94,13 +92,14 @@ assign(ReactDOMTextComponent.prototype, {
       }
     }
 
-    this._rootNodeID = rootID;
+    var domID = nativeContainerInfo._idCounter++;
+    this._domID = domID;
     this._nativeParent = nativeParent;
     if (transaction.useCreateElement) {
       var ownerDocument = nativeContainerInfo._ownerDocument;
       var el = ownerDocument.createElement('span');
       ReactDOMComponentTree.precacheNode(this, el);
-      DOMPropertyOperations.setAttributeForID(el, rootID);
+      DOMPropertyOperations.setAttributeForID(el, domID);
       var lazyTree = DOMLazyTree(el);
       DOMLazyTree.queueText(lazyTree, this._stringText);
       return lazyTree;
@@ -115,7 +114,7 @@ assign(ReactDOMTextComponent.prototype, {
       }
 
       return (
-        '<span ' + DOMPropertyOperations.createMarkupForID(rootID) + '>' +
+        '<span ' + DOMPropertyOperations.createMarkupForID(domID) + '>' +
           escapedText +
         '</span>'
       );
@@ -148,8 +147,7 @@ assign(ReactDOMTextComponent.prototype, {
   },
 
   unmountComponent: function() {
-    this._nativeNode = null;
-    ReactComponentBrowserEnvironment.unmountIDFromEnvironment(this._rootNodeID);
+    ReactDOMComponentTree.uncacheNode(this);
   },
 
 });
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js b/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
index 049ecf0b0a..85f4cfa4f0 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMTextComponent-test.js
@@ -13,22 +13,11 @@
 
 var React;
 var ReactDOM;
-var ReactDOMServer;
 
 describe('ReactDOMTextComponent', function() {
   beforeEach(function() {
     React = require('React');
     ReactDOM = require('ReactDOM');
-    ReactDOMServer = require('ReactDOMServer');
-  });
-
-  it('should escape the rootID', function() {
-    var ThisThingShouldBeEscaped = '">>> LULZ <<<"';
-    var ThisThingWasBeEscaped = '&quot;&gt;&gt;&gt; LULZ &lt;&lt;&lt;&quot;';
-    var thing = <div><span key={ThisThingShouldBeEscaped}>LULZ</span></div>;
-    var html = ReactDOMServer.renderToString(thing);
-    expect(html).not.toContain(ThisThingShouldBeEscaped);
-    expect(html).toContain(ThisThingWasBeEscaped);
   });
 
   it('updates a mounted text component in place', function() {
diff --git a/src/renderers/shared/reconciler/ReactMultiChild.js b/src/renderers/shared/reconciler/ReactMultiChild.js
index bfb9bda1f4..1b0be8c563 100644
--- a/src/renderers/shared/reconciler/ReactMultiChild.js
+++ b/src/renderers/shared/reconciler/ReactMultiChild.js
@@ -249,11 +249,9 @@ var ReactMultiChild = {
       for (var name in children) {
         if (children.hasOwnProperty(name)) {
           var child = children[name];
-          // Inlined for performance, see `ReactInstanceHandles.createReactID`.
-          var rootID = this._rootNodeID + name;
           var mountImage = ReactReconciler.mountComponent(
             child,
-            rootID,
+            name,
             transaction,
             this,
             this._nativeContainerInfo,
@@ -510,11 +508,9 @@ var ReactMultiChild = {
       index,
       transaction,
       context) {
-      // Inlined for performance, see `ReactInstanceHandles.createReactID`.
-      var rootID = this._rootNodeID + name;
       var mountImage = ReactReconciler.mountComponent(
         child,
-        rootID,
+        name,
         transaction,
         this,
         this._nativeContainerInfo,
diff --git a/src/renderers/shared/reconciler/__tests__/ReactIdentity-test.js b/src/renderers/shared/reconciler/__tests__/ReactIdentity-test.js
index 2639ffb2d3..f5918b4abf 100644
--- a/src/renderers/shared/reconciler/__tests__/ReactIdentity-test.js
+++ b/src/renderers/shared/reconciler/__tests__/ReactIdentity-test.js
@@ -13,7 +13,6 @@
 
 var React;
 var ReactDOM;
-var ReactDOMComponentTree;
 var ReactFragment;
 var ReactTestUtils;
 
@@ -23,85 +22,52 @@ describe('ReactIdentity', function() {
     jest.resetModuleRegistry();
     React = require('React');
     ReactDOM = require('ReactDOM');
-    ReactDOMComponentTree = require('ReactDOMComponentTree');
     ReactFragment = require('ReactFragment');
     ReactTestUtils = require('ReactTestUtils');
   });
 
-  var idExp = /^\.[^.]+(.*)$/;
-  function checkID(child, expectedID) {
-    // TODO: Node IDs are not public API; rewrite these tests.
-    var rootID = ReactDOMComponentTree.getInstanceFromNode(child)._rootNodeID;
-    var actual = idExp.exec(rootID);
-    var expected = idExp.exec(expectedID);
-    expect(actual).toBeTruthy();
-    expect(expected).toBeTruthy();
-    expect(actual[1]).toEqual(expected[1]);
-  }
-
   function frag(obj) {
     return ReactFragment.create(obj);
   }
 
-  it('should allow keyed objects to express identity', function() {
-    var instance =
-      <div>
-        {frag({
-          first: <div />,
-          second: <div />,
-        })}
-      </div>;
-
-    instance = ReactDOM.render(instance, document.createElement('div'));
-    var node = ReactDOM.findDOMNode(instance);
-    expect(node.childNodes.length).toBe(2);
-    checkID(node.childNodes[0], '.0.$first/=10');
-    checkID(node.childNodes[1], '.0.$second/=10');
-  });
-
   it('should allow key property to express identity', function() {
-    var instance =
-      <div>
-        <div key="apple" />
-        <div key="banana" />
-        <div key={0} />
-        <div key={123} />
+    var node;
+    var Component = (props) =>
+      <div ref={(c) => node = c}>
+        <div key={props.swap ? 'banana' : 'apple'} />
+        <div key={props.swap ? 'apple' : 'banana'} />
       </div>;
 
-    instance = ReactDOM.render(instance, document.createElement('div'));
-    var node = ReactDOM.findDOMNode(instance);
-    expect(node.childNodes.length).toBe(4);
-    checkID(node.childNodes[0], '.0.$apple');
-    checkID(node.childNodes[1], '.0.$banana');
-    checkID(node.childNodes[2], '.0.$0');
-    checkID(node.childNodes[3], '.0.$123');
+    var container = document.createElement('div');
+    ReactDOM.render(<Component />, container);
+    var origChildren = Array.from(node.childNodes);
+    ReactDOM.render(<Component swap={true} />, container);
+    var newChildren = Array.from(node.childNodes);
+    expect(origChildren[0]).toBe(newChildren[1]);
+    expect(origChildren[1]).toBe(newChildren[0]);
   });
 
-  it('should use instance identity', function() {
+  it('should use composite identity', function() {
 
     var Wrapper = React.createClass({
       render: function() {
-        return <a key="i_get_overwritten">{this.props.children}</a>;
+        return <a>{this.props.children}</a>;
       },
     });
 
-    var instance =
-      <div>
-        <Wrapper key="wrap1"><span key="squirrel" /></Wrapper>
-        <Wrapper key="wrap2"><span key="bunny" /></Wrapper>
-        <Wrapper><span key="chipmunk" /></Wrapper>
-      </div>;
+    var container = document.createElement('div');
+    var node1;
+    var node2;
+    ReactDOM.render(
+      <Wrapper key="wrap1"><span ref={(c) => node1 = c} /></Wrapper>,
+      container
+    );
+    ReactDOM.render(
+      <Wrapper key="wrap2"><span ref={(c) => node2 = c} /></Wrapper>,
+      container
+    );
 
-    instance = ReactDOM.render(instance, document.createElement('div'));
-    var node = ReactDOM.findDOMNode(instance);
-    expect(node.childNodes.length).toBe(3);
-
-    checkID(node.childNodes[0], '.0.$wrap1');
-    checkID(node.childNodes[0].firstChild, '.0.$wrap1.$squirrel');
-    checkID(node.childNodes[1], '.0.$wrap2');
-    checkID(node.childNodes[1].firstChild, '.0.$wrap2.$bunny');
-    checkID(node.childNodes[2], '.0.2');
-    checkID(node.childNodes[2].firstChild, '.0.2.$chipmunk');
+    expect(node1).not.toBe(node2);
   });
 
   function renderAComponentWithKeyIntoContainer(key, container) {
@@ -125,11 +91,6 @@ describe('ReactIdentity', function() {
 
     expect(ReactDOM.findDOMNode(span1)).not.toBe(null);
     expect(ReactDOM.findDOMNode(span2)).not.toBe(null);
-
-    key = key.replace(/=/g, '=0');
-    checkID(ReactDOM.findDOMNode(span1), '.0.$' + key);
-    key = key.replace(/\//g, '//');
-    checkID(ReactDOM.findDOMNode(span2), '.0.1:$' + key + '/=10');
   }
 
   it('should allow any character as a key, in a detached parent', function() {
diff --git a/src/renderers/shared/reconciler/__tests__/ReactMultiChildReconcile-test.js b/src/renderers/shared/reconciler/__tests__/ReactMultiChildReconcile-test.js
index 5ca3e4afb1..012691a52c 100644
--- a/src/renderers/shared/reconciler/__tests__/ReactMultiChildReconcile-test.js
+++ b/src/renderers/shared/reconciler/__tests__/ReactMultiChildReconcile-test.js
@@ -122,7 +122,7 @@ var FriendsStatusDisplay = React.createClass({
 });
 
 
-function getInteralStateByUserName(statusDisplays) {
+function getInternalStateByUserName(statusDisplays) {
   return mapObject(statusDisplays, function(statusDisplay, key) {
     return statusDisplay.getInternalState();
   });
@@ -201,7 +201,9 @@ function verifyDomOrderingAccurate(parentInstance, statusDisplays) {
       continue;
     }
     var statusDisplay = statusDisplays[username];
-    orderedLogicalIDs.push(ReactInstanceMap.get(statusDisplay)._rootNodeID);
+    orderedLogicalIDs.push(
+      ReactInstanceMap.get(statusDisplay)._renderedComponent._rootNodeID
+    );
   }
   expect(orderedDomIDs).toEqual(orderedLogicalIDs);
 }
@@ -217,7 +219,7 @@ function testPropsSequence(sequence) {
     container
   );
   var statusDisplays = parentInstance.getStatusDisplays();
-  var lastInternalStates = getInteralStateByUserName(statusDisplays);
+  var lastInternalStates = getInternalStateByUserName(statusDisplays);
   verifyStatuses(statusDisplays, sequence[0]);
 
   for (i = 1; i < sequence.length; i++) {
@@ -230,7 +232,7 @@ function testPropsSequence(sequence) {
     verifyStatesPreserved(lastInternalStates, statusDisplays);
     verifyDomOrderingAccurate(parentInstance, statusDisplays);
 
-    lastInternalStates = getInteralStateByUserName(statusDisplays);
+    lastInternalStates = getInternalStateByUserName(statusDisplays);
   }
 }