diff --git a/src/sheet-toolbar.cjsx b/src/sheet-toolbar.cjsx
index b6f2d972d..e3c48cc2e 100644
--- a/src/sheet-toolbar.cjsx
+++ b/src/sheet-toolbar.cjsx
@@ -71,13 +71,35 @@ class ToolbarBack extends React.Component
 
 class ToolbarWindowControls extends React.Component
   @displayName: 'ToolbarWindowControls'
+  constructor: (@props) ->
+    @state = {alt: false}
+
+  componentDidMount: =>
+    if process.platform is 'darwin'
+      window.addEventListener('keydown', @_onAlt)
+      window.addEventListener('keyup', @_onAlt)
+
+  componentWillUnmount: =>
+    if process.platform is 'darwin'
+      window.removeEventListener('keydown', @_onAlt)
+      window.removeEventListener('keyup', @_onAlt)
+
   render: =>
-    <div name="ToolbarWindowControls" className="toolbar-window-controls">
+    <div name="ToolbarWindowControls" className="toolbar-window-controls alt-#{@state.alt}">
       <button className="close" onClick={ -> atom.close()}></button>
       <button className="minimize" onClick={ -> atom.minimize()}></button>
-      <button className="maximize" onClick={ -> atom.maximize()}></button>
+      <button className="maximize" onClick={@_onMaximize}></button>
     </div>
 
+  _onAlt: (event) =>
+    @setState(alt: event.altKey) if @state.alt isnt event.altKey
+
+  _onMaximize: (event) =>
+    if process.platform is 'darwin' and not event.altKey
+      atom.setFullScreen(!atom.isFullScreen())
+    else
+      atom.maximize()
+
 class ToolbarMenuControl extends React.Component
   @displayName: 'ToolbarMenuControl'
   render: =>
diff --git a/static/images/application-frame/fullscreen@2x.png b/static/images/application-frame/fullscreen@2x.png
new file mode 100644
index 000000000..3f1be7fde
Binary files /dev/null and b/static/images/application-frame/fullscreen@2x.png differ
diff --git a/static/workspace.less b/static/workspace.less
index 619a1361e..3bba60e72 100644
--- a/static/workspace.less
+++ b/static/workspace.less
@@ -108,7 +108,12 @@ atom-workspace {
     background-image: url("images/application-frame/minimize@1x.png");
   }
   .maximize {
-    background-image: url("images/application-frame/maximize@1x.png");
+    background-image: url("images/application-frame/fullscreen@1x.png");
+  }
+  &.alt-true {
+    .maximize {
+      background-image: url("images/application-frame/maximize@1x.png");
+    }
   }
 }
 
@@ -121,7 +126,12 @@ atom-workspace {
       background-image: url("images/application-frame/minimize@2x.png");
     }
     .maximize {
-      background-image: url("images/application-frame/maximize@2x.png");
+      background-image: url("images/application-frame/fullscreen@2x.png");
+    }
+    &.alt-true {
+      .maximize {
+        background-image: url("images/application-frame/maximize@2x.png");
+      }
     }
   }
 }