diff --git a/.modernizr.json b/.modernizr.json
new file mode 100644
index 00000000..6d28fa86
--- /dev/null
+++ b/.modernizr.json
@@ -0,0 +1,12 @@
+{
+  "minify": true,
+  "classPrefix": "modernizr_",
+  "options": [
+    "setClasses"
+  ],
+  "feature-detects": [
+    "test/css/displaytable",
+    "test/css/flexbox",
+    "test/es5/specification"
+  ]
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index 275ef4c2..9ed43f6d 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,7 @@
   "style": "bundle.css",
   "scripts": {
     "reskindex": "reskindex vector -h src/skins/vector/header",
+    "build:modernizr": "modernizr -c .modernizr.json -d src/vector/modernizr.js",
     "build:css": "catw \"src/skins/vector/css/**/*.css\" -o vector/bundle.css -c uglifycss --no-watch",
     "build:compile": "babel --source-maps -d lib src",
     "build:bundle": "NODE_ENV=production webpack -p lib/vector/index.js vector/bundle.js",
@@ -29,6 +30,7 @@
     "linkifyjs": "^2.0.0-beta.4",
     "matrix-js-sdk": "^0.2.2",
     "matrix-react-sdk": "^0.0.1",
+    "modernizr": "^3.1.0",
     "q": "^1.4.1",
     "react": "^0.13.3",
     "react-loader": "^1.4.0"
diff --git a/src/skins/vector/css/pages/CompatibilityPage.css b/src/skins/vector/css/pages/CompatibilityPage.css
new file mode 100644
index 00000000..f3f032c9
--- /dev/null
+++ b/src/skins/vector/css/pages/CompatibilityPage.css
@@ -0,0 +1,19 @@
+.mx_CompatibilityPage {
+    width: 100%;
+    height: 100%;
+    background-color: #e55;
+}
+
+.mx_CompatibilityPage_box {
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    margin: auto;
+    width: 500px;
+    height: 300px;
+    border: 1px solid;
+    padding: 10px;
+    background-color: #fcc;
+}
\ No newline at end of file
diff --git a/src/skins/vector/views/pages/CompatibilityPage.js b/src/skins/vector/views/pages/CompatibilityPage.js
new file mode 100644
index 00000000..610630dc
--- /dev/null
+++ b/src/skins/vector/views/pages/CompatibilityPage.js
@@ -0,0 +1,58 @@
+/*
+Copyright 2015 OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+'use strict';
+
+var React = require('react');
+
+module.exports = React.createClass({
+    displayName: 'CompatibilityPage',
+    propTypes: {
+        onAccept: React.PropTypes.func
+    },
+
+    getDefaultProps: function() {
+        return {
+            onAccept: function() {} // NOP
+        };
+    },
+
+    onAccept: function() {
+        this.props.onAccept();
+    },
+
+    render: function() {
+
+        return (
+        <div className="mx_CompatibilityPage">
+            <div className="mx_CompatibilityPage_box">
+                <p>Sorry, your browser is <b>not</b> able to run Vector.</p>
+                <p>
+                Buttons and images may appear out of place, communication may
+                not be possible and all manner of chaos may be unleashed.
+                </p>
+                <p>
+                Though if you like taking risks with your life, you can still try it
+                out by clicking that you understand the risks involved.
+                </p>
+                <button onClick={this.onAccept}>
+                    I understand the risks and wish to continue
+                </button>
+            </div>
+        </div>
+        );
+    }
+});
diff --git a/src/vector/index.js b/src/vector/index.js
index 22db05a3..52e267ab 100644
--- a/src/vector/index.js
+++ b/src/vector/index.js
@@ -16,6 +16,7 @@ limitations under the License.
 
 'use strict';
 
+var RunModernizrTests = require("./modernizr"); // this side-effects a global
 var React = require("react");
 var sdk = require("matrix-react-sdk");
 sdk.loadSkin(require('../skins/vector/skindex'));
@@ -25,6 +26,33 @@ var qs = require("querystring");
 
 var lastLocationHashSet = null;
 
+function checkBrowserFeatures(featureList) {
+    if (!window.Modernizr) {
+        console.error("Cannot check features - Modernizr global is missing.");
+        return false;
+    }
+    var featureComplete = true;
+    for (var i = 0; i < featureList.length; i++) {
+        if (window.Modernizr[featureList[i]] === undefined) {
+            console.error(
+                "Looked for feature '%s' but Modernizr has no results for this. " +
+                "Has it been configured correctly?", featureList[i]
+            );
+            return false;
+        }
+        if (window.Modernizr[featureList[i]] === false) {
+            console.error("Browser missing feature: '%s'", featureList[i]);
+            // toggle flag rather than return early so we log all missing features
+            // rather than just the first.
+            featureComplete = false;
+        }
+    }
+    return featureComplete;
+}
+
+var validBrowser = checkBrowserFeatures([
+    "displaytable", "flexbox", "es5object", "es5function", "foo"
+]);
 
 // We want to support some name / value pairs in the fragment
 // so we're re-using query string like format
@@ -84,14 +112,11 @@ var makeRegistrationUrl = function() {
            '#/register';
 }
 
-var MatrixChat = sdk.getComponent('pages.MatrixChat');
-window.matrixChat = React.render(
-    <MatrixChat onNewScreen={onNewScreen} registrationUrl={makeRegistrationUrl()} />,
-    document.getElementById('matrixchat')
-);
-
 window.addEventListener('hashchange', onHashChange);
 window.onload = function() {
+    if (!validBrowser) {
+        return;
+    }
     routeUrl(window.location);
     loaded = true;
     if (lastLoadedScreen) {
@@ -100,3 +125,28 @@ window.onload = function() {
     }
 }
 
+function loadApp() {
+    if (validBrowser) {
+        var MatrixChat = sdk.getComponent('pages.MatrixChat');
+        window.matrixChat = React.render(
+            <MatrixChat onNewScreen={onNewScreen} registrationUrl={makeRegistrationUrl()} />,
+            document.getElementById('matrixchat')
+        );
+    }
+    else {
+        console.error("Browser is missing required features.");
+        // take to a different landing page to AWOOOOOGA at the user
+        var CompatibilityPage = require("../skins/vector/views/pages/CompatibilityPage");
+        window.matrixChat = React.render(
+            <CompatibilityPage onAccept={function() {
+                validBrowser = true;
+                console.log("User accepts the compatibility risks.");
+                loadApp();
+                window.onload(); // still do the same code paths for compatible clients
+            }} />,
+            document.getElementById('matrixchat')
+        );
+    }  
+}
+
+loadApp();
diff --git a/src/vector/modernizr.js b/src/vector/modernizr.js
new file mode 100644
index 00000000..f9641a76
--- /dev/null
+++ b/src/vector/modernizr.js
@@ -0,0 +1,3 @@
+/*! modernizr 3.1.0 (Custom Build) | MIT *
+ * http://modernizr.com/download/?-displaytable-es5-flexbox-cssclassprefix:modernizr_ !*/
+!function(window,document,undefined){function is(e,t){return typeof e===t}function testRunner(){var e,t,r,n,o,s,i;for(var d in tests){if(e=[],t=tests[d],t.name&&(e.push(t.name.toLowerCase()),t.options&&t.options.aliases&&t.options.aliases.length))for(r=0;r<t.options.aliases.length;r++)e.push(t.options.aliases[r].toLowerCase());for(n=is(t.fn,"function")?t.fn():t.fn,o=0;o<e.length;o++)s=e[o],i=s.split("."),1===i.length?Modernizr[i[0]]=n:(!Modernizr[i[0]]||Modernizr[i[0]]instanceof Boolean||(Modernizr[i[0]]=new Boolean(Modernizr[i[0]])),Modernizr[i[0]][i[1]]=n),classes.push((n?"":"no-")+i.join("-"))}}function setClasses(e){var t=docElement.className,r=Modernizr._config.classPrefix||"";if(isSVG&&(t=t.baseVal),Modernizr._config.enableJSClass){var n=new RegExp("(^|\\s)"+r+"no-js(\\s|$)");t=t.replace(n,"$1"+r+"js$2")}Modernizr._config.enableClasses&&(t+=" "+r+e.join(" "+r),isSVG?docElement.className.baseVal=t:docElement.className=t)}function createElement(){return"function"!=typeof document.createElement?document.createElement(arguments[0]):isSVG?document.createElementNS.call(document,"http://www.w3.org/2000/svg",arguments[0]):document.createElement.apply(document,arguments)}function getBody(){var e=document.body;return e||(e=createElement(isSVG?"svg":"body"),e.fake=!0),e}function injectElementWithStyles(e,t,r,n){var o,s,i,d,a="modernizr",l=createElement("div"),c=getBody();if(parseInt(r,10))for(;r--;)i=createElement("div"),i.id=n?n[r]:a+(r+1),l.appendChild(i);return o=createElement("style"),o.type="text/css",o.id="s"+a,(c.fake?c:l).appendChild(o),c.appendChild(l),o.styleSheet?o.styleSheet.cssText=e:o.appendChild(document.createTextNode(e)),l.id=a,c.fake&&(c.style.background="",c.style.overflow="hidden",d=docElement.style.overflow,docElement.style.overflow="hidden",docElement.appendChild(c)),s=t(l,e),c.fake?(c.parentNode.removeChild(c),docElement.style.overflow=d,docElement.offsetHeight):l.parentNode.removeChild(l),!!s}function contains(e,t){return!!~(""+e).indexOf(t)}function domToCSS(e){return e.replace(/([A-Z])/g,function(e,t){return"-"+t.toLowerCase()}).replace(/^ms-/,"-ms-")}function nativeTestProps(e,t){var r=e.length;if("CSS"in window&&"supports"in window.CSS){for(;r--;)if(window.CSS.supports(domToCSS(e[r]),t))return!0;return!1}if("CSSSupportsRule"in window){for(var n=[];r--;)n.push("("+domToCSS(e[r])+":"+t+")");return n=n.join(" or "),injectElementWithStyles("@supports ("+n+") { #modernizr { position: absolute; } }",function(e){return"absolute"==getComputedStyle(e,null).position})}return undefined}function cssToDOM(e){return e.replace(/([a-z])-([a-z])/g,function(e,t,r){return t+r.toUpperCase()}).replace(/^-/,"")}function testProps(e,t,r,n){function o(){i&&(delete mStyle.style,delete mStyle.modElem)}if(n=is(n,"undefined")?!1:n,!is(r,"undefined")){var s=nativeTestProps(e,r);if(!is(s,"undefined"))return s}for(var i,d,a,l,c,f=["modernizr","tspan"];!mStyle.style;)i=!0,mStyle.modElem=createElement(f.shift()),mStyle.style=mStyle.modElem.style;for(a=e.length,d=0;a>d;d++)if(l=e[d],c=mStyle.style[l],contains(l,"-")&&(l=cssToDOM(l)),mStyle.style[l]!==undefined){if(n||is(r,"undefined"))return o(),"pfx"==t?l:!0;try{mStyle.style[l]=r}catch(u){}if(mStyle.style[l]!=c)return o(),"pfx"==t?l:!0}return o(),!1}function fnBind(e,t){return function(){return e.apply(t,arguments)}}function testDOMProps(e,t,r){var n;for(var o in e)if(e[o]in t)return r===!1?e[o]:(n=t[e[o]],is(n,"function")?fnBind(n,r||t):n);return!1}function testPropsAll(e,t,r,n,o){var s=e.charAt(0).toUpperCase()+e.slice(1),i=(e+" "+cssomPrefixes.join(s+" ")+s).split(" ");return is(t,"string")||is(t,"undefined")?testProps(i,t,n,o):(i=(e+" "+domPrefixes.join(s+" ")+s).split(" "),testDOMProps(i,t,r))}function testAllProps(e,t,r){return testPropsAll(e,undefined,undefined,t,r)}var tests=[],ModernizrProto={_version:"3.1.0",_config:{classPrefix:"modernizr_",enableClasses:!0,enableJSClass:!0,usePrefixes:!0},_q:[],on:function(e,t){var r=this;setTimeout(function(){t(r[e])},0)},addTest:function(e,t,r){tests.push({name:e,fn:t,options:r})},addAsyncTest:function(e){tests.push({name:null,fn:e})}},Modernizr=function(){};Modernizr.prototype=ModernizrProto,Modernizr=new Modernizr;var classes=[],docElement=document.documentElement,isSVG="svg"===docElement.nodeName.toLowerCase(),testStyles=ModernizrProto.testStyles=injectElementWithStyles;testStyles("#modernizr{display: table; direction: ltr}#modernizr div{display: table-cell; padding: 10px}",function(e){var t,r=e.childNodes;t=r[0].offsetLeft<r[1].offsetLeft,Modernizr.addTest("displaytable",t,{aliases:["display-table"]})},2);var omPrefixes="Moz O ms Webkit",cssomPrefixes=ModernizrProto._config.usePrefixes?omPrefixes.split(" "):[];ModernizrProto._cssomPrefixes=cssomPrefixes;var modElem={elem:createElement("modernizr")};Modernizr._q.push(function(){delete modElem.elem});var mStyle={style:modElem.elem.style};Modernizr._q.unshift(function(){delete mStyle.style});var domPrefixes=ModernizrProto._config.usePrefixes?omPrefixes.toLowerCase().split(" "):[];ModernizrProto._domPrefixes=domPrefixes,ModernizrProto.testAllProps=testPropsAll,ModernizrProto.testAllProps=testAllProps,Modernizr.addTest("flexbox",testAllProps("flexBasis","1px",!0)),Modernizr.addTest("es5array",function(){return!!(Array.prototype&&Array.prototype.every&&Array.prototype.filter&&Array.prototype.forEach&&Array.prototype.indexOf&&Array.prototype.lastIndexOf&&Array.prototype.map&&Array.prototype.some&&Array.prototype.reduce&&Array.prototype.reduceRight&&Array.isArray)}),Modernizr.addTest("es5date",function(){var e="2013-04-12T06:06:37.307Z",t=!1;try{t=!!Date.parse(e)}catch(r){}return!!(Date.now&&Date.prototype&&Date.prototype.toISOString&&Date.prototype.toJSON&&t)}),Modernizr.addTest("es5function",function(){return!(!Function.prototype||!Function.prototype.bind)}),Modernizr.addTest("es5object",function(){return!!(Object.keys&&Object.create&&Object.getPrototypeOf&&Object.getOwnPropertyNames&&Object.isSealed&&Object.isFrozen&&Object.isExtensible&&Object.getOwnPropertyDescriptor&&Object.defineProperty&&Object.defineProperties&&Object.seal&&Object.freeze&&Object.preventExtensions)}),Modernizr.addTest("strictmode",function(){"use strict";return!this}()),Modernizr.addTest("es5string",function(){return!(!String.prototype||!String.prototype.trim)}),Modernizr.addTest("json","JSON"in window&&"parse"in JSON&&"stringify"in JSON),Modernizr.addTest("es5syntax",function(){var value,obj,stringAccess,getter,setter,reservedWords,zeroWidthChars;try{return stringAccess=eval('"foobar"[3] === "b"'),getter=eval("({ get x(){ return 1 } }).x === 1"),eval("({ set x(v){ value = v; } }).x = 1"),setter=1===value,eval("obj = ({ if: 1 })"),reservedWords=1===obj["if"],zeroWidthChars=eval("_‌‍ = true"),stringAccess&&getter&&setter&&reservedWords&&zeroWidthChars}catch(ignore){return!1}}),Modernizr.addTest("es5undefined",function(){var e,t;try{t=window.undefined,window.undefined=12345,e="undefined"==typeof window.undefined,window.undefined=t}catch(r){return!1}return e}),Modernizr.addTest("es5",function(){return!!(Modernizr.es5array&&Modernizr.es5date&&Modernizr.es5function&&Modernizr.es5object&&Modernizr.strictmode&&Modernizr.es5string&&Modernizr.json&&Modernizr.es5syntax&&Modernizr.es5undefined)}),testRunner(),setClasses(classes),delete ModernizrProto.addTest,delete ModernizrProto.addAsyncTest;for(var i=0;i<Modernizr._q.length;i++)Modernizr._q[i]();window.Modernizr=Modernizr}(window,document);
\ No newline at end of file