diff --git a/src/core/React.js b/src/core/React.js
index 2c63e8795b..511742b5c2 100644
--- a/src/core/React.js
+++ b/src/core/React.js
@@ -50,6 +50,7 @@ var React = {
   ),
   renderComponentToString: ReactServerRendering.renderComponentToString,
   unmountAndReleaseReactRootNode: ReactMount.unmountAndReleaseReactRootNode,
+  isValidClass: ReactCompositeComponent.isValidClass,
   isValidComponent: ReactComponent.isValidComponent
 };
 
diff --git a/src/core/ReactCompositeComponent.js b/src/core/ReactCompositeComponent.js
index aab39a4265..08edadb7ef 100644
--- a/src/core/ReactCompositeComponent.js
+++ b/src/core/ReactCompositeComponent.js
@@ -956,6 +956,19 @@ var ReactCompositeComponent = {
     return ConvenienceConstructor;
   },
 
+  /**
+   * Checks if a value is a valid component constructor.
+   *
+   * @param {*}
+   * @return {boolean}
+   * @public
+   */
+  isValidClass: function(componentClass) {
+    return componentClass instanceof Function &&
+           'componentConstructor' in componentClass &&
+           componentClass.componentConstructor instanceof Function;
+  },
+
   /**
    * TODO: Delete this when all callers have been updated to rely on this
    * behavior being the default.
diff --git a/src/core/__tests__/ReactCompositeComponent-test.js b/src/core/__tests__/ReactCompositeComponent-test.js
index 752ab19fb4..bc9db48ef8 100644
--- a/src/core/__tests__/ReactCompositeComponent-test.js
+++ b/src/core/__tests__/ReactCompositeComponent-test.js
@@ -381,4 +381,30 @@ describe('ReactCompositeComponent', function() {
     );
   });
 
+  it('should detect valid CompositeComponent classes', function() {
+    var Component = React.createClass({
+      render: function() {
+        return <div/>;
+      }
+    });
+
+    expect(React.isValidClass(Component)).toBe(true);
+  });
+
+  it('should detect invalid CompositeComponent classes', function() {
+    var FnComponent = function() {
+      return false;
+    }
+
+    var NullComponent = null;
+
+    var TrickFnComponent = function() {
+      return true;
+    }
+    TrickFnComponent.componentConstructor = true;
+
+    expect(React.isValidClass(FnComponent)).toBe(false);
+    expect(React.isValidClass(NullComponent)).toBe(false);
+    expect(React.isValidClass(TrickFnComponent)).toBe(false);
+  });
 });
diff --git a/src/core/__tests__/ReactDOM-test.js b/src/core/__tests__/ReactDOM-test.js
index fdd88c6757..bd7ce73fdb 100644
--- a/src/core/__tests__/ReactDOM-test.js
+++ b/src/core/__tests__/ReactDOM-test.js
@@ -23,11 +23,10 @@
 
 var React = require('React');
 var ReactDOM = require('ReactDOM');
-var ReactTestUtils = require('ReactTestUtils');
-var React = require('React');
 var ReactMount = require('ReactMount');
+var ReactTestUtils = require('ReactTestUtils');
 
-describe('ref swapping', function() {
+describe('ReactDOM', function() {
   // TODO: uncomment this test once we can run in phantom, which
   // supports real submit events.
   /*
@@ -115,4 +114,8 @@ describe('ref swapping', function() {
     var dog = root.childNodes[0];
     expect(dog.className).toBe('bigdog');
   });
+
+  it('should be a valid class', function() {
+    expect(React.isValidClass(ReactDOM.div)).toBe(true);
+  });
 });