diff --git a/src/RichText.js b/src/RichText.js
index 7e749bc24a..678a7de190 100644
--- a/src/RichText.js
+++ b/src/RichText.js
@@ -5,7 +5,8 @@ import {
     convertFromHTML,
     DefaultDraftBlockRenderMap,
     DefaultDraftInlineStyle,
-    CompositeDecorator
+    CompositeDecorator,
+    SelectionState
 } from 'draft-js';
 import * as sdk from  './index';
 
@@ -168,3 +169,28 @@ export function modifyText(contentState: ContentState, rangeToReplace: Selection
 
     return Modifier.replaceText(contentState, rangeToReplace, modifyFn(text), inlineStyle, entityKey);
 }
+
+/**
+ * Computes the plaintext offsets of the given SelectionState.
+ * Note that this inherently means we make assumptions about what that means (no separator between ContentBlocks, etc)
+ * Used by autocomplete to show completions when the current selection lies within, or at the edges of a command.
+ */
+export function getTextSelectionOffsets(selectionState: SelectionState,
+                                        contentBlocks: Array<ContentBlock>): {start: number, end: number} {
+    let offset = 0, start = 0, end = 0;
+    for(let block of contentBlocks) {
+        if (selectionState.getStartKey() == block.getKey()) {
+            start = offset + selectionState.getStartOffset();
+        }
+        if (selectionState.getEndKey() == block.getKey()) {
+            end = offset + selectionState.getEndOffset();
+            break;
+        }
+        offset += block.getLength();
+    }
+
+    return {
+        start,
+        end
+    }
+}
diff --git a/src/autocomplete/AutocompleteProvider.js b/src/autocomplete/AutocompleteProvider.js
index 61158d2b56..f741e085b0 100644
--- a/src/autocomplete/AutocompleteProvider.js
+++ b/src/autocomplete/AutocompleteProvider.js
@@ -1,4 +1,41 @@
+import Q from 'q';
+
 export default class AutocompleteProvider {
+    constructor(commandRegex?: RegExp, fuseOpts?: any) {
+        if(commandRegex) {
+            if(!commandRegex.global) {
+                throw new Error('commandRegex must have global flag set');
+            }
+            this.commandRegex = commandRegex;
+        }
+    }
+
+    /**
+     * Of the matched commands in the query, returns the first that contains or is contained by the selection, or null.
+     */
+    getCurrentCommand(query: string, selection: {start: number, end: number}): ?Array<string> {
+        if(this.commandRegex == null)
+            return null;
+
+        let match = null;
+        while((match = this.commandRegex.exec(query)) != null) {
+            let matchStart = match.index,
+                matchEnd = matchStart + match[0].length;
+
+            console.log(match);
+            
+            if(selection.start <= matchEnd && selection.end >= matchStart) {
+                return match;
+            }
+        }
+        this.commandRegex.lastIndex = 0;
+        return null;
+    }
+
+    getCompletions(query: String, selection: {start: number, end: number}) {
+        return Q.when([]);
+    }
+
     getName(): string {
         return 'Default Provider';
     }
diff --git a/src/autocomplete/Autocompleter.js b/src/autocomplete/Autocompleter.js
index 95669d5e0f..6b66d2fbdc 100644
--- a/src/autocomplete/Autocompleter.js
+++ b/src/autocomplete/Autocompleter.js
@@ -12,10 +12,10 @@ const PROVIDERS = [
     EmojiProvider
 ].map(completer => completer.getInstance());
 
-export function getCompletions(query: String) {
+export function getCompletions(query: string, selection: {start: number, end: number}) {
     return PROVIDERS.map(provider => {
         return {
-            completions: provider.getCompletions(query),
+            completions: provider.getCompletions(query, selection),
             provider
         };
     });
diff --git a/src/autocomplete/CommandProvider.js b/src/autocomplete/CommandProvider.js
index 7b950c0ed0..30b448d7f2 100644
--- a/src/autocomplete/CommandProvider.js
+++ b/src/autocomplete/CommandProvider.js
@@ -39,22 +39,23 @@ const COMMANDS = [
     }
 ];
 
+let COMMAND_RE = /(^\/\w*)/g;
+
 let instance = null;
 
 export default class CommandProvider extends AutocompleteProvider {
     constructor() {
-        super();
+        super(COMMAND_RE);
         this.fuse = new Fuse(COMMANDS, {
            keys: ['command', 'args', 'description']
         });
     }
 
-    getCompletions(query: String) {
+    getCompletions(query: string, selection: {start: number, end: number}) {
         let completions = [];
-        const matches = query.match(/(^\/\w*)/);
-        if(!!matches) {
-            const command = matches[0];
-            completions = this.fuse.search(command).map(result => {
+        const command = this.getCurrentCommand(query, selection);
+        if(command) {
+            completions = this.fuse.search(command[0]).map(result => {
                 return {
                     title: result.command,
                     subtitle: result.args,
diff --git a/src/autocomplete/DuckDuckGoProvider.js b/src/autocomplete/DuckDuckGoProvider.js
index 496ce72e46..b2bf27a21a 100644
--- a/src/autocomplete/DuckDuckGoProvider.js
+++ b/src/autocomplete/DuckDuckGoProvider.js
@@ -2,23 +2,27 @@ import AutocompleteProvider from './AutocompleteProvider';
 import Q from 'q';
 import 'whatwg-fetch';
 
-const DDG_REGEX = /\/ddg\s+(.+)$/;
+const DDG_REGEX = /\/ddg\s+(.+)$/g;
 const REFERER = 'vector';
 
 let instance = null;
 
 export default class DuckDuckGoProvider extends AutocompleteProvider {
+    constructor() {
+        super(DDG_REGEX);
+    }
+    
     static getQueryUri(query: String) {
         return `http://api.duckduckgo.com/?q=${encodeURIComponent(query)}`
          + `&format=json&no_redirect=1&no_html=1&t=${encodeURIComponent(REFERER)}`;
     }
 
-    getCompletions(query: String) {
-        let match = DDG_REGEX.exec(query);
-        if(!query || !match)
+    getCompletions(query: string, selection: {start: number, end: number}) {
+        let command = this.getCurrentCommand(query, selection);
+        if(!query || !command)
             return Q.when([]);
 
-        return fetch(DuckDuckGoProvider.getQueryUri(match[1]), {
+        return fetch(DuckDuckGoProvider.getQueryUri(command[1]), {
             method: 'GET'
         })
             .then(response => response.json())
diff --git a/src/autocomplete/EmojiProvider.js b/src/autocomplete/EmojiProvider.js
index 684414d72a..e1b5f3ea38 100644
--- a/src/autocomplete/EmojiProvider.js
+++ b/src/autocomplete/EmojiProvider.js
@@ -10,16 +10,15 @@ let instance = null;
 
 export default class EmojiProvider extends AutocompleteProvider {
     constructor() {
-        super();
+        super(EMOJI_REGEX);
         this.fuse = new Fuse(EMOJI_SHORTNAMES);
     }
 
-    getCompletions(query: String) {
+    getCompletions(query: string, selection: {start: number, end: number}) {
         let completions = [];
-        let matches = query.match(EMOJI_REGEX);
-        let command = matches && matches[0];
+        let command = this.getCurrentCommand(query, selection);
         if(command) {
-            completions = this.fuse.search(command).map(result => {
+            completions = this.fuse.search(command[0]).map(result => {
                 let shortname = EMOJI_SHORTNAMES[result];
                 let imageHTML = shortnameToImage(shortname);
                 return {
diff --git a/src/autocomplete/RoomProvider.js b/src/autocomplete/RoomProvider.js
index b1232358b5..8b5650e7a7 100644
--- a/src/autocomplete/RoomProvider.js
+++ b/src/autocomplete/RoomProvider.js
@@ -9,17 +9,18 @@ let instance = null;
 
 export default class RoomProvider extends AutocompleteProvider {
     constructor() {
-        super();
+        super(ROOM_REGEX, {
+            keys: ['displayName', 'userId']
+        });
         this.fuse = new Fuse([], {
            keys: ['name', 'roomId', 'aliases']
         });
     }
 
-    getCompletions(query: String) {
+    getCompletions(query: string, selection: {start: number, end: number}) {
         let client = MatrixClientPeg.get();
         let completions = [];
-        const matches = query.match(ROOM_REGEX);
-        const command = matches && matches[0];
+        const command = this.getCurrentCommand(query, selection);
         if(command) {
             // the only reason we need to do this is because Fuse only matches on properties
             this.fuse.set(client.getRooms().filter(room => !!room).map(room => {
@@ -29,7 +30,7 @@ export default class RoomProvider extends AutocompleteProvider {
                     aliases: room.getAliases()
                 };
             }));
-            completions = this.fuse.search(command).map(room => {
+            completions = this.fuse.search(command[0]).map(room => {
                 return {
                     title: room.name,
                     subtitle: room.roomId
diff --git a/src/autocomplete/UserProvider.js b/src/autocomplete/UserProvider.js
index 51a85adaf1..3edb2bf00c 100644
--- a/src/autocomplete/UserProvider.js
+++ b/src/autocomplete/UserProvider.js
@@ -2,26 +2,27 @@ import AutocompleteProvider from './AutocompleteProvider';
 import Q from 'q';
 import Fuse from 'fuse.js';
 
-const ROOM_REGEX = /@[^\s]*/g;
+const USER_REGEX = /@[^\s]*/g;
 
 let instance = null;
 
 export default class UserProvider extends AutocompleteProvider {
     constructor() {
-        super();
+        super(USER_REGEX, {
+            keys: ['displayName', 'userId']
+        });
         this.users = [];
         this.fuse = new Fuse([], {
             keys: ['displayName', 'userId']
         })
     }
 
-    getCompletions(query: String) {
+    getCompletions(query: string, selection: {start: number, end: number}) {
         let completions = [];
-        let matches = query.match(ROOM_REGEX);
-        let command = matches && matches[0];
+        let command = this.getCurrentCommand(query, selection);
         if(command) {
             this.fuse.set(this.users);
-            completions = this.fuse.search(command).map(user => {
+            completions = this.fuse.search(command[0]).map(user => {
                 return {
                     title: user.displayName || user.userId,
                     description: user.userId
diff --git a/src/components/views/rooms/Autocomplete.js b/src/components/views/rooms/Autocomplete.js
index 0218a88195..babd349c31 100644
--- a/src/components/views/rooms/Autocomplete.js
+++ b/src/components/views/rooms/Autocomplete.js
@@ -7,27 +7,27 @@ export default class Autocomplete extends React.Component {
     constructor(props) {
         super(props);
         this.state = {
-            completions: []
+            completions: [],
+
+            // how far down the completion list we are
+            selectionOffset: 0
         };
     }
 
     componentWillReceiveProps(props, state) {
         if(props.query == this.props.query) return;
 
-        getCompletions(props.query).map(completionResult => {
+        getCompletions(props.query, props.selection).map(completionResult => {
             try {
-                // console.log(`${completionResult.provider.getName()}: ${JSON.stringify(completionResult.completions)}`);
                 completionResult.completions.then(completions => {
                     let i = this.state.completions.findIndex(
                         completion => completion.provider === completionResult.provider
                     );
 
                     i = i == -1 ? this.state.completions.length : i;
-                    // console.log(completionResult);
                     let newCompletions = Object.assign([], this.state.completions);
                     completionResult.completions = completions;
                     newCompletions[i] = completionResult;
-                    // console.log(newCompletions);
                     this.setState({
                         completions: newCompletions
                     });
@@ -42,8 +42,7 @@ export default class Autocomplete extends React.Component {
     }
 
     render() {
-        const renderedCompletions = this.state.completions.map((completionResult, i) => {
-            // console.log(completionResult);
+        let renderedCompletions = this.state.completions.map((completionResult, i) => {
             let completions = completionResult.completions.map((completion, i) => {
                 let Component = completion.component;
                 if(Component) {
diff --git a/src/components/views/rooms/MessageComposer.js b/src/components/views/rooms/MessageComposer.js
index 5373ca4dc8..ce1ced2b59 100644
--- a/src/components/views/rooms/MessageComposer.js
+++ b/src/components/views/rooms/MessageComposer.js
@@ -36,7 +36,8 @@ export default class MessageComposer extends React.Component {
         this.onInputContentChanged = this.onInputContentChanged.bind(this);
 
         this.state = {
-            autocompleteQuery: ''
+            autocompleteQuery: '',
+            selection: null
         };
     }
 
@@ -121,11 +122,11 @@ export default class MessageComposer extends React.Component {
         });
     }
 
-    onInputContentChanged(content: string) {
+    onInputContentChanged(content: string, selection: {start: number, end: number}) {
         this.setState({
-            autocompleteQuery: content
+            autocompleteQuery: content,
+            selection
         });
-        console.log(content);
     }
 
     render() {
@@ -200,7 +201,7 @@ export default class MessageComposer extends React.Component {
         return (
             <div className="mx_MessageComposer mx_fadable" style={{ opacity: this.props.opacity }}>
                 <div className="mx_MessageComposer_autocomplete_wrapper">
-                    <Autocomplete query={this.state.autocompleteQuery} />
+                    <Autocomplete query={this.state.autocompleteQuery} selection={this.state.selection} />
                 </div>
                 <div className="mx_MessageComposer_wrapper">
                     <div className="mx_MessageComposer_row">
diff --git a/src/components/views/rooms/MessageComposerInput.js b/src/components/views/rooms/MessageComposerInput.js
index d82e9fb6c7..9b615e7e4e 100644
--- a/src/components/views/rooms/MessageComposerInput.js
+++ b/src/components/views/rooms/MessageComposerInput.js
@@ -352,7 +352,9 @@ export default class MessageComposerInput extends React.Component {
         }
 
         if(this.props.onContentChanged) {
-            this.props.onContentChanged(editorState.getCurrentContent().getPlainText());
+            this.props.onContentChanged(editorState.getCurrentContent().getPlainText(),
+                RichText.getTextSelectionOffsets(editorState.getSelection(),
+                    editorState.getCurrentContent().getBlocksAsArray()));
         }
     }