diff --git a/src/components/structures/MatrixChat.js b/src/components/structures/MatrixChat.js
index c47109db94..79e93bb990 100644
--- a/src/components/structures/MatrixChat.js
+++ b/src/components/structures/MatrixChat.js
@@ -25,6 +25,7 @@ var SdkConfig = require("../../SdkConfig");
 var ContextualMenu = require("./ContextualMenu");
 var RoomListSorter = require("../../RoomListSorter");
 var UserActivity = require("../../UserActivity");
+var UserSettingsStore = require('../../UserSettingsStore');
 var Presence = require("../../Presence");
 var dis = require("../../dispatcher");
 
@@ -456,6 +457,9 @@ module.exports = React.createClass({
                     middleOpacity: payload.middleOpacity,
                 });
                 break;
+            case 'set_theme':
+                this._onSetTheme(payload.value);
+                break;
             case 'on_logged_in':
                 this._onLoggedIn();
                 break;
@@ -584,6 +588,44 @@ module.exports = React.createClass({
     _onLoadCompleted: function() {
         this.props.onLoadCompleted();
         this.setState({loading: false});
+
+        // set up the right theme.
+        // XXX: this will temporarily flicker the wrong CSS.
+        dis.dispatch({
+            action: 'set_theme',
+            value: UserSettingsStore.getSyncedSetting('theme')
+        });
+    },
+
+    /**
+     * Called whenever someone changes the theme
+     */
+    _onSetTheme: function(theme) {
+        if (!theme) {
+            theme = 'light';
+        }
+
+        var i, a;
+        for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
+            var href = a.getAttribute("href");
+            if (href.startsWith("theme-")) {
+                if (href.startsWith("theme-" + theme + ".")) {
+                    a.disabled = false;
+                }
+                else {
+                    a.disabled = true;
+                }
+            }
+        }
+
+        if (theme === 'dark') {
+            // abuse the tinter to change all the SVG's #fff to #2d2d2d
+            // XXX: obviously this shouldn't be hardcoded here.
+            Tinter.tint(undefined, undefined, undefined, '#2d2d2d');
+        }
+        else {
+            Tinter.tint(undefined, undefined, undefined, '#ffffff');
+        }
     },
 
     /**
diff --git a/src/components/structures/UserSettings.js b/src/components/structures/UserSettings.js
index a41eab3a76..ebfd6dc0a7 100644
--- a/src/components/structures/UserSettings.js
+++ b/src/components/structures/UserSettings.js
@@ -363,7 +363,23 @@ module.exports = React.createClass({
         */
         ];
 
+        var themes = [
+            {
+                id: 'theme',
+                label: 'Light theme',
+                value: 'light',
+            },
+            {
+                id: 'theme',
+                label: 'Dark theme',
+                value: 'dark',
+            }
+        ];
+
         var syncedSettings = UserSettingsStore.getSyncedSettings();
+        if (!syncedSettings.theme) {
+            syncedSettings.theme = 'light';
+        }
 
         return (
             <div>
@@ -379,19 +395,42 @@ module.exports = React.createClass({
                             Disable inline URL previews by default
                         </label>
                     </div>
+                    { settingsLabels.map( setting => {
+                        return <div className="mx_UserSettings_toggle" key={ setting.id }>
+                            <input id={ setting.id }
+                                   type="checkbox"
+                                   defaultChecked={ syncedSettings[setting.id] }
+                                   onChange={ e => UserSettingsStore.setSyncedSetting(setting.id, e.target.checked) }
+                            />
+                            <label htmlFor={ setting.id }>
+                                { setting.label }
+                            </label>
+                        </div>
+                    })}
+                    { themes.map( setting => {
+                        return <div className="mx_UserSettings_toggle" key={ setting.id + "_" + setting.value }>
+                            <input id={ setting.id + "_" + setting.value }
+                                   type="radio"
+                                   name={ setting.id }
+                                   value={ setting.value }
+                                   defaultChecked={ syncedSettings[setting.id] === setting.value }
+                                   onChange={ e => {
+                                            if (e.target.checked) {
+                                                UserSettingsStore.setSyncedSetting(setting.id, setting.value)
+                                            }
+                                            dis.dispatch({
+                                                action: 'set_theme',
+                                                value: setting.value,
+                                            });
+                                        }
+                                   }
+                            />
+                            <label htmlFor={ setting.id + "_" + setting.value }>
+                                { setting.label }
+                            </label>
+                        </div>
+                    })}
                 </div>
-                { settingsLabels.forEach( setting => {
-                    <div className="mx_UserSettings_toggle">
-                        <input id={ setting.id }
-                               type="checkbox"
-                               defaultChecked={ syncedSettings[setting.id] }
-                               onChange={ e => UserSettingsStore.setSyncedSetting(setting.id, e.target.checked) }
-                        />
-                        <label htmlFor={ setting.id }>
-                            { settings.label }
-                        </label>
-                    </div>
-                })}
             </div>
         );
     },