diff --git a/src/isomorphic/ReactDebugTool.js b/src/isomorphic/ReactDebugTool.js
index 2435a613f4006..4d2c2a3536a5e 100644
--- a/src/isomorphic/ReactDebugTool.js
+++ b/src/isomorphic/ReactDebugTool.js
@@ -11,6 +11,7 @@
 
 'use strict';
 
+var ReactInvalidSetStateWarningDevTool = require('ReactInvalidSetStateWarningDevTool');
 var warning = require('warning');
 
 var eventHandlers = [];
@@ -48,6 +49,15 @@ var ReactDebugTool = {
       }
     }
   },
+  onBeginProcessingChildContext() {
+    emitEvent('onBeginProcessingChildContext');
+  },
+  onEndProcessingChildContext() {
+    emitEvent('onEndProcessingChildContext');
+  },
+  onSetState() {
+    emitEvent('onSetState');
+  },
   onMountRootComponent(internalInstance) {
     emitEvent('onMountRootComponent', internalInstance);
   },
@@ -62,4 +72,6 @@ var ReactDebugTool = {
   },
 };
 
+ReactDebugTool.addDevtool(ReactInvalidSetStateWarningDevTool);
+
 module.exports = ReactDebugTool;
diff --git a/src/isomorphic/devtools/ReactInvalidSetStateWarningDevTool.js b/src/isomorphic/devtools/ReactInvalidSetStateWarningDevTool.js
new file mode 100644
index 0000000000000..74275187cb323
--- /dev/null
+++ b/src/isomorphic/devtools/ReactInvalidSetStateWarningDevTool.js
@@ -0,0 +1,39 @@
+/**
+ * Copyright 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule ReactInvalidSetStateWarningDevTool
+ */
+
+'use strict';
+
+var warning = require('warning');
+
+if (__DEV__) {
+  var processingChildContext = false;
+
+  var warnInvalidSetState = function() {
+    warning(
+      !processingChildContext,
+      'setState(...): Cannot call setState() inside getChildContext()'
+    );
+  };
+}
+
+var ReactInvalidSetStateWarningDevTool = {
+  onBeginProcessingChildContext() {
+    processingChildContext = true;
+  },
+  onEndProcessingChildContext() {
+    processingChildContext = false;
+  },
+  onSetState() {
+    warnInvalidSetState();
+  },
+};
+
+module.exports = ReactInvalidSetStateWarningDevTool;
diff --git a/src/isomorphic/modern/class/ReactComponent.js b/src/isomorphic/modern/class/ReactComponent.js
index 2882b56602d8c..a7d8b4baa92c8 100644
--- a/src/isomorphic/modern/class/ReactComponent.js
+++ b/src/isomorphic/modern/class/ReactComponent.js
@@ -12,6 +12,7 @@
 'use strict';
 
 var ReactNoopUpdateQueue = require('ReactNoopUpdateQueue');
+var ReactInstrumentation = require('ReactInstrumentation');
 
 var canDefineProperty = require('canDefineProperty');
 var emptyObject = require('emptyObject');
@@ -66,6 +67,7 @@ ReactComponent.prototype.setState = function(partialState, callback) {
     'function which returns an object of state variables.'
   );
   if (__DEV__) {
+    ReactInstrumentation.debugTool.onSetState();
     warning(
       partialState != null,
       'setState(...): You passed an undefined or null state object; ' +
diff --git a/src/renderers/shared/reconciler/ReactCompositeComponent.js b/src/renderers/shared/reconciler/ReactCompositeComponent.js
index 68fd901bd90d4..9e636294b55d8 100644
--- a/src/renderers/shared/reconciler/ReactCompositeComponent.js
+++ b/src/renderers/shared/reconciler/ReactCompositeComponent.js
@@ -16,6 +16,7 @@ var ReactCurrentOwner = require('ReactCurrentOwner');
 var ReactElement = require('ReactElement');
 var ReactErrorUtils = require('ReactErrorUtils');
 var ReactInstanceMap = require('ReactInstanceMap');
+var ReactInstrumentation = require('ReactInstrumentation');
 var ReactNodeTypes = require('ReactNodeTypes');
 var ReactPerf = require('ReactPerf');
 var ReactPropTypeLocations = require('ReactPropTypeLocations');
@@ -496,7 +497,13 @@ var ReactCompositeComponentMixin = {
   _processChildContext: function(currentContext) {
     var Component = this._currentElement.type;
     var inst = this._instance;
+    if (__DEV__) {
+      ReactInstrumentation.debugTool.onBeginProcessingChildContext();
+    }
     var childContext = inst.getChildContext && inst.getChildContext();
+    if (__DEV__) {
+      ReactInstrumentation.debugTool.onEndProcessingChildContext();
+    }
     if (childContext) {
       invariant(
         typeof Component.childContextTypes === 'object',
diff --git a/src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js b/src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js
index 456b01325851f..9d5b06229315f 100644
--- a/src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js
+++ b/src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js
@@ -424,6 +424,35 @@ describe('ReactCompositeComponent', function() {
     expect(instance2.state.value).toBe(1);
   });
 
+  it('should warn about `setState` in getChildContext', function() {
+    var container = document.createElement('div');
+
+    var renderPasses = 0;
+
+    var Component = React.createClass({
+      getInitialState: function() {
+        return {value: 0};
+      },
+      getChildContext: function() {
+        if (this.state.value === 0) {
+          this.setState({ value: 1 });
+        }
+      },
+      render: function() {
+        renderPasses++;
+        return <div />;
+      },
+    });
+    expect(console.error.calls.length).toBe(0);
+    var instance = ReactDOM.render(<Component />, container);
+    expect(renderPasses).toBe(2);
+    expect(instance.state.value).toBe(1);
+    expect(console.error.calls.length).toBe(1);
+    expect(console.error.argsForCall[0][0]).toBe(
+      'Warning: setState(...): Cannot call setState() inside getChildContext()'
+    );
+  });
+
   it('should cleanup even if render() fatals', function() {
     var BadComponent = React.createClass({
       render: function() {