diff --git a/src/renderers/dom/fiber/ReactDOMFiberComponent.js b/src/renderers/dom/fiber/ReactDOMFiberComponent.js
index 0ce5956146a38..4fe120cdaf479 100644
--- a/src/renderers/dom/fiber/ReactDOMFiberComponent.js
+++ b/src/renderers/dom/fiber/ReactDOMFiberComponent.js
@@ -40,10 +40,10 @@ if (__DEV__) {
   var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
   var {validateProperties: validateARIAProperties} = ReactDOMInvalidARIAHook;
   var {
-    validateProperties: validateInputPropertes,
+    validateProperties: validateInputProperties,
   } = ReactDOMNullInputValuePropHook;
   var {
-    validateProperties: validateUnknownPropertes,
+    validateProperties: validateUnknownProperties,
   } = ReactDOMUnknownPropertyHook;
 }
 
@@ -72,8 +72,8 @@ if (__DEV__) {
 
   var validatePropertiesInDevelopment = function(type, props) {
     validateARIAProperties(type, props);
-    validateInputPropertes(type, props);
-    validateUnknownPropertes(type, props);
+    validateInputProperties(type, props);
+    validateUnknownProperties(type, props);
   };
 
   var warnForTextDifference = function(serverText: string, clientText: string) {
@@ -233,7 +233,7 @@ function setInitialDOMProperties(
     } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
       // Noop
     } else if (registrationNameModules.hasOwnProperty(propKey)) {
-      if (nextProp) {
+      if (nextProp != null) {
         if (__DEV__ && typeof nextProp !== 'function') {
           warnForInvalidEventListener(propKey, nextProp);
         }
@@ -305,11 +305,9 @@ var ReactDOMFiberComponent = {
     if (namespaceURI === HTML_NAMESPACE) {
       namespaceURI = getIntrinsicNamespace(type);
     }
-    if (__DEV__) {
-      var isCustomComponentTag = isCustomComponent(type, props);
-    }
     if (namespaceURI === HTML_NAMESPACE) {
       if (__DEV__) {
+        var isCustomComponentTag = isCustomComponent(type, props);
         // Should this check be gated by parent namespace? Not sure we want to
         // allow <SVG> or <mATH>.
         warning(
@@ -328,7 +326,7 @@ var ReactDOMFiberComponent = {
         // This is guaranteed to yield a script element.
         var firstChild = ((div.firstChild: any): HTMLScriptElement);
         domElement = div.removeChild(firstChild);
-      } else if (props.is) {
+      } else if (typeof props.is === 'string') {
         // $FlowIssue `createElement` should be updated for Web Components
         domElement = ownerDocument.createElement(type, {is: props.is});
       } else {
@@ -707,7 +705,7 @@ var ReactDOMFiberComponent = {
       } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
         // Noop
       } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (nextProp) {
+        if (nextProp != null) {
           // We eagerly listen to this even though we haven't committed yet.
           if (__DEV__ && typeof nextProp !== 'function') {
             warnForInvalidEventListener(propKey, nextProp);
@@ -951,7 +949,7 @@ var ReactDOMFiberComponent = {
           }
         }
       } else if (registrationNameModules.hasOwnProperty(propKey)) {
-        if (nextProp) {
+        if (nextProp != null) {
           if (__DEV__ && typeof nextProp !== 'function') {
             warnForInvalidEventListener(propKey, nextProp);
           }
diff --git a/src/renderers/dom/shared/DOMMarkupOperations.js b/src/renderers/dom/shared/DOMMarkupOperations.js
index 9323f7182776c..772133625bf20 100644
--- a/src/renderers/dom/shared/DOMMarkupOperations.js
+++ b/src/renderers/dom/shared/DOMMarkupOperations.js
@@ -99,8 +99,12 @@ var DOMMarkupOperations = {
         (propertyInfo.hasOverloadedBooleanValue && value === true)
       ) {
         return attributeName + '=""';
+      } else if (
+        typeof value !== 'boolean' ||
+        DOMProperty.shouldAttributeAcceptBooleanValue(name)
+      ) {
+        return attributeName + '=' + quoteAttributeValueForBrowser(value);
       }
-      return attributeName + '=' + quoteAttributeValueForBrowser(value);
     } else if (DOMProperty.shouldSetAttribute(name, value)) {
       if (value == null) {
         return '';
diff --git a/src/renderers/dom/shared/DOMProperty.js b/src/renderers/dom/shared/DOMProperty.js
index d6ddf9c3b3ae5..be3c8a1233b40 100644
--- a/src/renderers/dom/shared/DOMProperty.js
+++ b/src/renderers/dom/shared/DOMProperty.js
@@ -17,14 +17,12 @@ var invariant = require('fbjs/lib/invariant');
 // case insensitive checks
 var RESERVED_PROPS = {
   children: true,
-  dangerouslysetinnerhtml: true,
-  autofocus: true,
-  defaultvalue: true,
-  defaultchecked: true,
-  innerhtml: true,
-  suppresscontenteditablewarning: true,
-  onfocusin: true,
-  onfocusout: true,
+  dangerouslySetInnerHTML: true,
+  autoFocus: true,
+  defaultValue: true,
+  defaultChecked: true,
+  innerHTML: true,
+  suppressContentEditableWarning: true,
   style: true,
 };
 
@@ -42,6 +40,7 @@ var DOMPropertyInjection = {
   HAS_NUMERIC_VALUE: 0x8,
   HAS_POSITIVE_NUMERIC_VALUE: 0x10 | 0x8,
   HAS_OVERLOADED_BOOLEAN_VALUE: 0x20,
+  HAS_STRING_BOOLEAN_VALUE: 0x40,
 
   /**
    * Inject some specialized knowledge about the DOM. This takes a config object
@@ -103,6 +102,10 @@ var DOMPropertyInjection = {
           propConfig,
           Injection.HAS_OVERLOADED_BOOLEAN_VALUE,
         ),
+        hasStringBooleanValue: checkMask(
+          propConfig,
+          Injection.HAS_STRING_BOOLEAN_VALUE,
+        ),
       };
       invariant(
         propertyInfo.hasBooleanValue +
@@ -201,26 +204,21 @@ var DOMProperty = {
     if (DOMProperty.isReservedProp(name)) {
       return false;
     }
-
+    if (
+      (name[0] === 'o' || name[0] === 'O') &&
+      (name[1] === 'n' || name[1] === 'N')
+    ) {
+      return false;
+    }
     if (value === null) {
       return true;
     }
-
-    var lowerCased = name.toLowerCase();
-
-    var propertyInfo = DOMProperty.properties[name];
-
     switch (typeof value) {
       case 'boolean':
-        if (propertyInfo) {
-          return true;
-        }
-        var prefix = lowerCased.slice(0, 5);
-        return prefix === 'data-' || prefix === 'aria-';
+        return DOMProperty.shouldAttributeAcceptBooleanValue(name);
       case 'undefined':
       case 'number':
       case 'string':
-        return true;
       case 'object':
         return true;
       default:
@@ -235,6 +233,22 @@ var DOMProperty = {
       : null;
   },
 
+  shouldAttributeAcceptBooleanValue(name) {
+    if (DOMProperty.isReservedProp(name)) {
+      return true;
+    }
+    let propertyInfo = DOMProperty.getPropertyInfo(name);
+    if (propertyInfo) {
+      return (
+        propertyInfo.hasBooleanValue ||
+        propertyInfo.hasStringBooleanValue ||
+        propertyInfo.hasOverloadedBooleanValue
+      );
+    }
+    var prefix = name.toLowerCase().slice(0, 5);
+    return prefix === 'data-' || prefix === 'aria-';
+  },
+
   /**
    * Checks to see if a property name is within the list of properties
    * reserved for internal React operations. These properties should
@@ -245,7 +259,7 @@ var DOMProperty = {
    * @return {boolean} If the name is within reserved props
    */
   isReservedProp(name) {
-    return RESERVED_PROPS.hasOwnProperty(name.toLowerCase());
+    return RESERVED_PROPS.hasOwnProperty(name);
   },
 
   injection: DOMPropertyInjection,
diff --git a/src/renderers/dom/shared/HTMLDOMPropertyConfig.js b/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
index ed3808c7f7dc7..19af1eadc0e8c 100644
--- a/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
+++ b/src/renderers/dom/shared/HTMLDOMPropertyConfig.js
@@ -20,6 +20,7 @@ var HAS_POSITIVE_NUMERIC_VALUE =
   DOMProperty.injection.HAS_POSITIVE_NUMERIC_VALUE;
 var HAS_OVERLOADED_BOOLEAN_VALUE =
   DOMProperty.injection.HAS_OVERLOADED_BOOLEAN_VALUE;
+var HAS_STRING_BOOLEAN_VALUE = DOMProperty.injection.HAS_STRING_BOOLEAN_VALUE;
 
 var HTMLDOMPropertyConfig = {
   // When adding attributes to this list, be sure to also add them to
@@ -27,6 +28,9 @@ var HTMLDOMPropertyConfig = {
   // name warnings.
   Properties: {
     allowFullScreen: HAS_BOOLEAN_VALUE,
+    // IE only true/false iFrame attribute
+    // https://msdn.microsoft.com/en-us/library/ms533072(v=vs.85).aspx
+    allowTransparency: HAS_STRING_BOOLEAN_VALUE,
     // specifies target context for links with `preload` type
     async: HAS_BOOLEAN_VALUE,
     // autoFocus is polyfilled/normalized by AutoFocusUtils
@@ -35,11 +39,13 @@ var HTMLDOMPropertyConfig = {
     capture: HAS_BOOLEAN_VALUE,
     checked: MUST_USE_PROPERTY | HAS_BOOLEAN_VALUE,
     cols: HAS_POSITIVE_NUMERIC_VALUE,
+    contentEditable: HAS_STRING_BOOLEAN_VALUE,
     controls: HAS_BOOLEAN_VALUE,
     default: HAS_BOOLEAN_VALUE,
     defer: HAS_BOOLEAN_VALUE,
     disabled: HAS_BOOLEAN_VALUE,
     download: HAS_OVERLOADED_BOOLEAN_VALUE,
+    draggable: HAS_STRING_BOOLEAN_VALUE,
     formNoValidate: HAS_BOOLEAN_VALUE,
     hidden: HAS_BOOLEAN_VALUE,
     loop: HAS_BOOLEAN_VALUE,
@@ -62,6 +68,7 @@ var HTMLDOMPropertyConfig = {
     start: HAS_NUMERIC_VALUE,
     // support for projecting regular DOM Elements via V1 named slots ( shadow dom )
     span: HAS_POSITIVE_NUMERIC_VALUE,
+    spellCheck: HAS_STRING_BOOLEAN_VALUE,
     // Style must be explicitly set in the attribute list. React components
     // expect a style object
     style: 0,
@@ -75,22 +82,8 @@ var HTMLDOMPropertyConfig = {
     htmlFor: 0,
     httpEquiv: 0,
     // Attributes with mutation methods must be specified in the whitelist
-    value: 0,
-    // The following attributes expect boolean values. They must be in
-    // the whitelist to allow boolean attribute assignment:
-    autoComplete: 0,
-    // IE only true/false iFrame attribute
-    // https://msdn.microsoft.com/en-us/library/ms533072(v=vs.85).aspx
-    allowTransparency: 0,
-    contentEditable: 0,
-    draggable: 0,
-    spellCheck: 0,
-    // autoCapitalize and autoCorrect are supported in Mobile Safari for
-    // keyboard hints.
-    autoCapitalize: 0,
-    autoCorrect: 0,
-    // autoSave allows WebKit/Blink to persist values of input fields on page reloads
-    autoSave: 0,
+    // Set the string boolean flag to allow the behavior
+    value: HAS_STRING_BOOLEAN_VALUE,
   },
   DOMAttributeNames: {
     acceptCharset: 'accept-charset',
diff --git a/src/renderers/dom/shared/SVGDOMPropertyConfig.js b/src/renderers/dom/shared/SVGDOMPropertyConfig.js
index 46db12aa4250d..0254d8ee0c20c 100644
--- a/src/renderers/dom/shared/SVGDOMPropertyConfig.js
+++ b/src/renderers/dom/shared/SVGDOMPropertyConfig.js
@@ -11,6 +11,10 @@
 
 'use strict';
 
+var DOMProperty = require('DOMProperty');
+
+var {HAS_STRING_BOOLEAN_VALUE} = DOMProperty.injection;
+
 var NS = {
   xlink: 'http://www.w3.org/1999/xlink',
   xml: 'http://www.w3.org/XML/1998/namespace',
@@ -113,15 +117,19 @@ var ATTRS = [
   'xmlns:xlink',
   'xml:lang',
   'xml:space',
-  // The following attributes expect boolean values. They must be in
-  // the whitelist to allow boolean attribute assignment:
-  'autoReverse',
-  'externalResourcesRequired',
-  'preserveAlpha',
 ];
 
 var SVGDOMPropertyConfig = {
-  Properties: {},
+  Properties: {
+    autoReverse: HAS_STRING_BOOLEAN_VALUE,
+    externalResourcesRequired: HAS_STRING_BOOLEAN_VALUE,
+    preserveAlpha: HAS_STRING_BOOLEAN_VALUE,
+  },
+  DOMAttributeNames: {
+    autoReverse: 'autoReverse',
+    externalResourcesRequired: 'externalResourcesRequired',
+    preserveAlpha: 'preserveAlpha',
+  },
   DOMAttributeNamespaces: {
     xlinkActuate: NS.xlink,
     xlinkArcrole: NS.xlink,
@@ -134,7 +142,6 @@ var SVGDOMPropertyConfig = {
     xmlLang: NS.xml,
     xmlSpace: NS.xml,
   },
-  DOMAttributeNames: {},
 };
 
 var CAMELIZE = /[\-\:]([a-z])/g;
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
index 981c9d3ed2b41..b37e4e647971a 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
@@ -178,6 +178,65 @@ describe('ReactDOMComponent', () => {
       );
     });
 
+    it('should warn for unknown string event handlers', () => {
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<div onUnknown="alert(&quot;hack&quot;)" />, container);
+      expect(container.firstChild.hasAttribute('onUnknown')).toBe(false);
+      expect(container.firstChild.onUnknown).toBe(undefined);
+      ReactDOM.render(<div onunknown="alert(&quot;hack&quot;)" />, container);
+      expect(container.firstChild.hasAttribute('onunknown')).toBe(false);
+      expect(container.firstChild.onunknown).toBe(undefined);
+      ReactDOM.render(<div on-unknown="alert(&quot;hack&quot;)" />, container);
+      expect(container.firstChild.hasAttribute('on-unknown')).toBe(false);
+      expect(container.firstChild['on-unknown']).toBe(undefined);
+      expectDev(console.error.calls.count(0)).toBe(3);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Unknown event handler property `onUnknown`. It will be ignored.\n    in div (at **)',
+      );
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
+        'Warning: Unknown event handler property `onunknown`. It will be ignored.\n    in div (at **)',
+      );
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(2)[0])).toBe(
+        'Warning: Unknown event handler property `on-unknown`. It will be ignored.\n    in div (at **)',
+      );
+    });
+
+    it('should warn for unknown function event handlers', () => {
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<div onUnknown={function() {}} />, container);
+      expect(container.firstChild.hasAttribute('onUnknown')).toBe(false);
+      expect(container.firstChild.onUnknown).toBe(undefined);
+      ReactDOM.render(<div onunknown={function() {}} />, container);
+      expect(container.firstChild.hasAttribute('onunknown')).toBe(false);
+      expect(container.firstChild.onunknown).toBe(undefined);
+      ReactDOM.render(<div on-unknown={function() {}} />, container);
+      expect(container.firstChild.hasAttribute('on-unknown')).toBe(false);
+      expect(container.firstChild['on-unknown']).toBe(undefined);
+      expectDev(console.error.calls.count(0)).toBe(3);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Unknown event handler property `onUnknown`. It will be ignored.\n    in div (at **)',
+      );
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(1)[0])).toBe(
+        'Warning: Unknown event handler property `onunknown`. It will be ignored.\n    in div (at **)',
+      );
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(2)[0])).toBe(
+        'Warning: Unknown event handler property `on-unknown`. It will be ignored.\n    in div (at **)',
+      );
+    });
+
+    it('should warn for badly cased React attributes', () => {
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<div CHILDREN="5" />, container);
+      expect(container.firstChild.getAttribute('CHILDREN')).toBe('5');
+      expectDev(console.error.calls.count(0)).toBe(1);
+      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+        'Warning: Invalid DOM property `CHILDREN`. Did you mean `children`?\n    in div (at **)',
+      );
+    });
+
     it('should not warn for "0" as a unitless style value', () => {
       spyOn(console, 'error');
 
@@ -635,12 +694,24 @@ describe('ReactDOMComponent', () => {
       expect(nodeValueSetter.mock.calls.length).toBe(3);
     });
 
-    it('should ignore attribute whitelist for elements with the "is: attribute', () => {
+    it('should ignore attribute whitelist for elements with the "is" attribute', () => {
       var container = document.createElement('div');
       ReactDOM.render(<button is="test" cowabunga="chevynova" />, container);
       expect(container.firstChild.hasAttribute('cowabunga')).toBe(true);
     });
 
+    it('should warn about non-string "is" attribute', () => {
+      spyOn(console, 'error');
+      var container = document.createElement('div');
+      ReactDOM.render(<button is={function() {}} />, container);
+
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Received a `function` for string attribute `is`. If this is expected, cast ' +
+          'the value to a string.',
+      );
+    });
+
     it('should not update when switching between null/undefined', () => {
       var container = document.createElement('div');
       var node = ReactDOM.render(<div />, container);
@@ -815,6 +886,16 @@ describe('ReactDOMComponent', () => {
       );
     });
 
+    it('should warn on props reserved for future use', () => {
+      spyOn(console, 'error');
+      ReactTestUtils.renderIntoDocument(<div aria="hello" />);
+      expectDev(console.error.calls.count()).toBe(1);
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'The `aria` attribute is reserved for future use in React. ' +
+          'Pass individual `aria-` attributes instead.',
+      );
+    });
+
     it('should warn if the tag is unrecognized', () => {
       spyOn(console, 'error');
 
@@ -2003,7 +2084,7 @@ describe('ReactDOMComponent', () => {
       expect(el.hasAttribute('whatever')).toBe(false);
 
       expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Warning: Invalid prop `whatever` on <div> tag',
+        'Warning: Received `true` for non-boolean attribute `whatever`',
       );
     });
 
@@ -2016,7 +2097,7 @@ describe('ReactDOMComponent', () => {
       expect(el.hasAttribute('whatever')).toBe(false);
 
       expectDev(console.error.calls.argsFor(0)[0]).toContain(
-        'Warning: Invalid prop `whatever` on <div> tag',
+        'Warning: Received `true` for non-boolean attribute `whatever`',
       );
     });
 
@@ -2096,10 +2177,8 @@ describe('ReactDOMComponent', () => {
 
   describe('Object stringification', function() {
     it('allows objects on known properties', function() {
-      var el = ReactTestUtils.renderIntoDocument(
-        <div allowTransparency={{}} />,
-      );
-      expect(el.getAttribute('allowtransparency')).toBe('[object Object]');
+      var el = ReactTestUtils.renderIntoDocument(<div acceptCharset={{}} />);
+      expect(el.getAttribute('accept-charset')).toBe('[object Object]');
     });
 
     it('should pass objects as attributes if they define toString', () => {
@@ -2157,4 +2236,76 @@ describe('ReactDOMComponent', () => {
       expect(el.getAttribute('ajaxify')).toBe('ajaxy');
     });
   });
+
+  describe('String boolean attributes', function() {
+    it('does not assign string boolean attributes for custom attributes', function() {
+      spyOn(console, 'error');
+
+      var el = ReactTestUtils.renderIntoDocument(<div whatever={true} />);
+
+      expect(el.hasAttribute('whatever')).toBe(false);
+
+      expectDev(console.error.calls.argsFor(0)[0]).toContain(
+        'Warning: Received `true` for non-boolean attribute `whatever`.',
+      );
+    });
+
+    it('stringifies the boolean true for allowed attributes', function() {
+      var el = ReactTestUtils.renderIntoDocument(<div spellCheck={true} />);
+
+      expect(el.getAttribute('spellCheck')).toBe('true');
+    });
+
+    it('stringifies the boolean false for allowed attributes', function() {
+      var el = ReactTestUtils.renderIntoDocument(<div spellCheck={false} />);
+
+      expect(el.getAttribute('spellCheck')).toBe('false');
+    });
+
+    it('stringifies implicit booleans for allowed attributes', function() {
+      // eslint-disable-next-line react/jsx-boolean-value
+      var el = ReactTestUtils.renderIntoDocument(<div spellCheck />);
+
+      expect(el.getAttribute('spellCheck')).toBe('true');
+    });
+  });
+
+  if (ReactDOMFeatureFlags.useFiber) {
+    // This is currently broken (and has been broken for a while).
+    // We had a fix based on reading namespace, but it was too convoluted.
+    // TODO: a proper fix that would happen at the diffing stage.
+    describe.skip('Hyphenated SVG elements', function() {
+      it('the font-face element is not a custom element', function() {
+        spyOn(console, 'error');
+        var el = ReactTestUtils.renderIntoDocument(
+          <svg><font-face x-height={false} /></svg>,
+        );
+
+        expect(el.querySelector('font-face').hasAttribute('x-height')).toBe(
+          false,
+        );
+
+        expectDev(console.error.calls.count()).toBe(1);
+        expectDev(console.error.calls.argsFor(0)[0]).toContain(
+          'Warning: Invalid DOM property `x-height`. Did you mean `xHeight`',
+        );
+      });
+
+      it('the font-face element does not allow unknown boolean values', function() {
+        spyOn(console, 'error');
+        var el = ReactTestUtils.renderIntoDocument(
+          <svg><font-face whatever={false} /></svg>,
+        );
+
+        expect(el.querySelector('font-face').hasAttribute('whatever')).toBe(
+          false,
+        );
+
+        expectDev(console.error.calls.count()).toBe(1);
+        expectDev(console.error.calls.argsFor(0)[0]).toContain(
+          'Warning: Received `false` for non-boolean attribute `whatever`.',
+        );
+      });
+    });
+  }
 });
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js b/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
index 2f5cd7034c2f3..0d4256117053b 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js
@@ -596,16 +596,14 @@ describe('ReactDOMServerIntegration', () => {
         expect(e.getAttribute('class')).toBe('');
       });
 
-      // this probably is just masking programmer error, but it is existing behavior.
-      itRenders('className prop with true value', async render => {
-        const e = await render(<div className={true} />);
-        expect(e.getAttribute('class')).toBe('true');
+      itRenders('no className prop with true value', async render => {
+        const e = await render(<div className={true} />, 1);
+        expect(e.hasAttribute('class')).toBe(false);
       });
 
-      // this probably is just masking programmer error, but it is existing behavior.
-      itRenders('className prop with false value', async render => {
-        const e = await render(<div className={false} />);
-        expect(e.getAttribute('class')).toBe('false');
+      itRenders('no className prop with false value', async render => {
+        const e = await render(<div className={false} />, 1);
+        expect(e.hasAttribute('class')).toBe(false);
       });
 
       itRenders('no className prop with null value', async render => {
@@ -663,16 +661,14 @@ describe('ReactDOMServerIntegration', () => {
         expect(e.getAttribute('for')).toBe('');
       });
 
-      // this probably is just masking programmer error, but it is existing behavior.
-      itRenders('htmlFor prop with true value', async render => {
-        const e = await render(<div htmlFor={true} />);
-        expect(e.getAttribute('for')).toBe('true');
+      itRenders('no htmlFor prop with true value', async render => {
+        const e = await render(<div htmlFor={true} />, 1);
+        expect(e.hasAttribute('for')).toBe(false);
       });
 
-      // this probably is just masking programmer error, but it is existing behavior.
-      itRenders('htmlFor prop with false value', async render => {
-        const e = await render(<div htmlFor={false} />);
-        expect(e.getAttribute('for')).toBe('false');
+      itRenders('no htmlFor prop with false value', async render => {
+        const e = await render(<div htmlFor={false} />, 1);
+        expect(e.hasAttribute('for')).toBe(false);
       });
 
       itRenders('no htmlFor prop with null value', async render => {
@@ -849,6 +845,12 @@ describe('ReactDOMServerIntegration', () => {
         const e = await render(<div aria-label={null} />);
         expect(e.hasAttribute('aria-label')).toBe(false);
       });
+
+      itRenders('"aria" attribute with a warning', async render => {
+        // Reserved for future use.
+        const e = await render(<div aria="hello" />, 1);
+        expect(e.getAttribute('aria')).toBe('hello');
+      });
     });
 
     describe('cased attributes', function() {
@@ -892,6 +894,17 @@ describe('ReactDOMServerIntegration', () => {
         expect(e.getAttribute('data-foo')).toBe('bar');
       });
 
+      itRenders('badly cased reserved attributes', async render => {
+        const e = await render(<div CHILDREN="5" />, 1);
+        expect(e.getAttribute('CHILDREN')).toBe('5');
+      });
+
+      itRenders('"data" attribute', async render => {
+        // For `<object />` acts as `src`.
+        const e = await render(<object data="hello" />);
+        expect(e.getAttribute('data')).toBe('hello');
+      });
+
       itRenders('no unknown data- attributes with null value', async render => {
         const e = await render(<div data-foo={null} />);
         expect(e.hasAttribute('data-foo')).toBe(false);
@@ -954,6 +967,19 @@ describe('ReactDOMServerIntegration', () => {
         },
       );
 
+      // This is currently broken (and has been broken for a while).
+      // We had a fix based on reading namespace, but it was too convoluted.
+      // TODO: a proper fix that would happen at the diffing stage.
+      //
+      // itRenders(
+      //   'known SVG attributes for elements with dashes in tag',
+      //   async render => {
+      //     const e = await render(<svg><font-face accentHeight={10} /></svg>);
+      //     expect(e.firstChild.hasAttribute('accentHeight')).toBe(false);
+      //     expect(e.firstChild.getAttribute('accent-height')).toBe('10');
+      //   },
+      // );
+
       itRenders('cased custom attributes', async render => {
         const e = await render(<div fooBar="test" />);
         expect(e.getAttribute('fooBar')).toBe('test');
@@ -966,6 +992,14 @@ describe('ReactDOMServerIntegration', () => {
       expect(e.getAttribute('onClick')).toBe(null);
       expect(e.getAttribute('click')).toBe(null);
     });
+
+    itRenders('no unknown events', async render => {
+      const e = await render(
+        <div onunknownevent="alert(&quot;hack&quot;)" />,
+        1,
+      );
+      expect(e.getAttribute('onunknownevent')).toBe(null);
+    });
   });
 
   describe('elements and children', function() {
diff --git a/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js b/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
index 7ae5f553bca9f..705c5aa207d20 100644
--- a/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
+++ b/src/renderers/dom/shared/hooks/ReactDOMInvalidARIAHook.js
@@ -12,6 +12,7 @@
 'use strict';
 
 var DOMProperty = require('DOMProperty');
+var isCustomComponent = require('isCustomComponent');
 
 var warnedProperties = {};
 var rARIA = new RegExp('^(aria)-[' + DOMProperty.ATTRIBUTE_NAME_CHAR + ']*$');
@@ -145,7 +146,7 @@ function warnInvalidARIAProps(type, props, debugID) {
 }
 
 function validateProperties(type, props, debugID /* Stack only */) {
-  if (type.indexOf('-') >= 0 || props.is) {
+  if (isCustomComponent(type, props)) {
     return;
   }
   warnInvalidARIAProps(type, props, debugID);
diff --git a/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js b/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
index 0864104d3e5d8..1ce2a90fecb63 100644
--- a/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
+++ b/src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js
@@ -13,6 +13,7 @@
 
 var DOMProperty = require('DOMProperty');
 var EventPluginRegistry = require('EventPluginRegistry');
+var isCustomComponent = require('isCustomComponent');
 
 if (__DEV__) {
   var warning = require('fbjs/lib/warning');
@@ -78,6 +79,17 @@ if (__DEV__) {
       return true;
     }
 
+    if (lowerCasedName.indexOf('on') === 0) {
+      warning(
+        false,
+        'Unknown event handler property `%s`. It will be ignored.%s',
+        name,
+        getStackAddendum(debugID),
+      );
+      warnedProperties[name] = true;
+      return true;
+    }
+
     // Let the ARIA attribute hook validate ARIA attributes
     if (ARIA_NAME_REGEX.test(name)) {
       return true;
@@ -104,6 +116,33 @@ if (__DEV__) {
       return true;
     }
 
+    if (lowerCasedName === 'aria') {
+      warning(
+        false,
+        'The `aria` attribute is reserved for future use in React. ' +
+          'Pass individual `aria-` attributes instead.',
+      );
+      warnedProperties[name] = true;
+      return true;
+    }
+
+    if (
+      lowerCasedName === 'is' &&
+      value !== null &&
+      value !== undefined &&
+      typeof value !== 'string'
+    ) {
+      warning(
+        false,
+        'Received a `%s` for string attribute `is`. If this is expected, cast ' +
+          'the value to a string.%s',
+        typeof value,
+        getStackAddendum(debugID),
+      );
+      warnedProperties[name] = true;
+      return true;
+    }
+
     if (typeof value === 'number' && isNaN(value)) {
       warning(
         false,
@@ -132,6 +171,19 @@ if (__DEV__) {
       }
     }
 
+    if (typeof value === 'boolean') {
+      warning(
+        DOMProperty.shouldAttributeAcceptBooleanValue(name),
+        'Received `%s` for non-boolean attribute `%s`. If this is expected, cast ' +
+          'the value to a string.%s',
+        value,
+        name,
+        getStackAddendum(debugID),
+      );
+      warnedProperties[name] = true;
+      return true;
+    }
+
     // Now that we've validated casing, do not validate
     // data types for reserved props
     if (DOMProperty.isReservedProp(name)) {
@@ -154,23 +206,10 @@ var warnUnknownProperties = function(type, props, debugID) {
     var isValid = validateProperty(type, key, props[key], debugID);
     if (!isValid) {
       unknownProps.push(key);
-      var value = props[key];
-      if (typeof value === 'object' && value !== null) {
-        warning(
-          false,
-          'The %s prop on <%s> is not a known property, and was given an object.' +
-            'Remove it, or it will appear in the ' +
-            'DOM after a future React update.%s',
-          key,
-          type,
-          getStackAddendum(debugID),
-        );
-      }
     }
   }
 
   var unknownPropString = unknownProps.map(prop => '`' + prop + '`').join(', ');
-
   if (unknownProps.length === 1) {
     warning(
       false,
@@ -195,7 +234,7 @@ var warnUnknownProperties = function(type, props, debugID) {
 };
 
 function validateProperties(type, props, debugID /* Stack only */) {
-  if (type.indexOf('-') >= 0 || props.is) {
+  if (isCustomComponent(type, props)) {
     return;
   }
   warnUnknownProperties(type, props, debugID);
diff --git a/src/renderers/dom/shared/hooks/possibleStandardNames.js b/src/renderers/dom/shared/hooks/possibleStandardNames.js
index 2d0a81771ece6..57b6cdb1e908e 100644
--- a/src/renderers/dom/shared/hooks/possibleStandardNames.js
+++ b/src/renderers/dom/shared/hooks/possibleStandardNames.js
@@ -64,7 +64,7 @@ var possibleStandardNames = {
   enctype: 'encType',
   for: 'htmlFor',
   form: 'form',
-  formMethod: 'formMethod',
+  formmethod: 'formMethod',
   formaction: 'formAction',
   formenctype: 'formEncType',
   formnovalidate: 'formNoValidate',
@@ -99,7 +99,7 @@ var possibleStandardNames = {
   loop: 'loop',
   low: 'low',
   manifest: 'manifest',
-  marginWidth: 'marginWidth',
+  marginwidth: 'marginWidth',
   marginheight: 'marginHeight',
   max: 'max',
   maxlength: 'maxLength',
@@ -107,7 +107,7 @@ var possibleStandardNames = {
   mediagroup: 'mediaGroup',
   method: 'method',
   min: 'min',
-  minLength: 'minlength',
+  minlength: 'minLength',
   multiple: 'multiple',
   muted: 'muted',
   name: 'name',
@@ -236,7 +236,7 @@ var possibleStandardNames = {
   filter: 'filter',
   filterres: 'filterRes',
   filterunits: 'filterUnits',
-  floodOpacity: 'floodOpacity',
+  floodopacity: 'floodOpacity',
   'flood-opacity': 'floodOpacity',
   floodcolor: 'floodColor',
   'flood-color': 'floodColor',
diff --git a/src/renderers/dom/shared/utils/isCustomComponent.js b/src/renderers/dom/shared/utils/isCustomComponent.js
index 2563a1e2b5a13..0d730a877e8f8 100644
--- a/src/renderers/dom/shared/utils/isCustomComponent.js
+++ b/src/renderers/dom/shared/utils/isCustomComponent.js
@@ -7,12 +7,13 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule isCustomComponent
+ * @flow
  */
 
 'use strict';
 
-function isCustomComponent(tagName, props) {
-  return tagName.indexOf('-') >= 0 || props.is != null;
+function isCustomComponent(tagName: string, props: Object) {
+  return tagName.indexOf('-') >= 0 || typeof props.is === 'string';
 }
 
 module.exports = isCustomComponent;
diff --git a/src/renderers/dom/stack/client/ReactDOMComponent.js b/src/renderers/dom/stack/client/ReactDOMComponent.js
index 8f20ebb891393..daf427fcc9e7c 100644
--- a/src/renderers/dom/stack/client/ReactDOMComponent.js
+++ b/src/renderers/dom/stack/client/ReactDOMComponent.js
@@ -480,9 +480,6 @@ ReactDOMComponent.Mixin = {
 
     assertValidProps(this, props);
 
-    if (__DEV__) {
-      var isCustomComponentTag = isCustomComponent(this._tag, props);
-    }
     // We create tags in the namespace of their parent container, except HTML
     // tags get no namespace.
     var namespaceURI;
@@ -500,6 +497,9 @@ ReactDOMComponent.Mixin = {
     ) {
       namespaceURI = Namespaces.html;
     }
+    if (__DEV__) {
+      var isCustomComponentTag = isCustomComponent(this._tag, props);
+    }
     if (namespaceURI === Namespaces.html) {
       if (__DEV__) {
         warning(
@@ -548,7 +548,7 @@ ReactDOMComponent.Mixin = {
           var div = ownerDocument.createElement('div');
           div.innerHTML = `<${type}></${type}>`;
           el = div.removeChild(div.firstChild);
-        } else if (props.is) {
+        } else if (typeof props.is === 'string') {
           el = ownerDocument.createElement(type, {is: props.is});
         } else {
           // Separate else branch instead of using `props.is || undefined` above because of a Firefox bug.
diff --git a/src/renderers/shared/server/ReactPartialRenderer.js b/src/renderers/shared/server/ReactPartialRenderer.js
index 64cdb8109b9a5..f86e45b6b5351 100644
--- a/src/renderers/shared/server/ReactPartialRenderer.js
+++ b/src/renderers/shared/server/ReactPartialRenderer.js
@@ -28,6 +28,7 @@ var hyphenateStyleName = require('fbjs/lib/hyphenateStyleName');
 var invariant = require('fbjs/lib/invariant');
 var memoizeStringOnly = require('fbjs/lib/memoizeStringOnly');
 var omittedCloseTags = require('omittedCloseTags');
+var isCustomComponent = require('isCustomComponent');
 
 var toArray = React.Children.toArray;
 
@@ -39,15 +40,15 @@ if (__DEV__) {
     validateProperties: validateARIAProperties,
   } = require('ReactDOMInvalidARIAHook');
   var {
-    validateProperties: validateInputPropertes,
+    validateProperties: validateInputProperties,
   } = require('ReactDOMNullInputValuePropHook');
   var {
-    validateProperties: validateUnknownPropertes,
+    validateProperties: validateUnknownProperties,
   } = require('ReactDOMUnknownPropertyHook');
   var validatePropertiesInDevelopment = function(type, props) {
     validateARIAProperties(type, props);
-    validateInputPropertes(type, props);
-    validateUnknownPropertes(type, props);
+    validateInputProperties(type, props);
+    validateUnknownProperties(type, props);
   };
 
   var describeComponentFrame = require('describeComponentFrame');
@@ -254,14 +255,11 @@ var RESERVED_PROPS = {
   suppressContentEditableWarning: null,
 };
 
-function isCustomComponent(tagName, props) {
-  return tagName.indexOf('-') >= 0 || props.is != null;
-}
-
 function createOpenTagMarkup(
   tagVerbatim,
   tagLowercase,
   props,
+  namespace,
   makeStaticMarkup,
   isRootElement,
   instForDebug,
@@ -786,6 +784,7 @@ class ReactDOMServerRenderer {
       element.type,
       tag,
       props,
+      namespace,
       this.makeStaticMarkup,
       this.stack.length === 1,
       null,