diff --git a/src/components/WindowTopBar.js b/src/components/WindowTopBar.js
index 6bb4cbd62a..fdba502ed2 100644
--- a/src/components/WindowTopBar.js
+++ b/src/components/WindowTopBar.js
@@ -27,7 +27,7 @@ export class WindowTopBar extends Component {
     const {
       removeWindow, windowId, classes, toggleWindowSideBar, t, windowDraggable,
       maximizeWindow, maximized, minimizeWindow, focused, allowClose, allowMaximize,
-      focusWindow, allowFullscreen, allowTopMenuButton, allowWindowSideBar,
+      focusWindow, allowFullscreen, allowTopMenuButton, allowWindowSideBar, sideBarOpen,
     } = this.props;
 
     return (
@@ -46,7 +46,8 @@ export class WindowTopBar extends Component {
           >
             {allowWindowSideBar && (
               <MiradorMenuButton
-                aria-label={t('toggleWindowSideBar')}
+                aria-expanded={sideBarOpen}
+                aria-label={sideBarOpen ? t('hideWindowSideBar') : t('showWindowSideBar')}
                 onClick={toggleWindowSideBar}
               >
                 <MenuIcon />
@@ -100,6 +101,7 @@ WindowTopBar.propTypes = {
   maximized: PropTypes.bool,
   maximizeWindow: PropTypes.func,
   minimizeWindow: PropTypes.func,
+  sideBarOpen: PropTypes.bool,
   removeWindow: PropTypes.func.isRequired,
   t: PropTypes.func,
   toggleWindowSideBar: PropTypes.func.isRequired,
@@ -118,6 +120,7 @@ WindowTopBar.defaultProps = {
   maximized: false,
   maximizeWindow: () => {},
   minimizeWindow: () => {},
+  sideBarOpen: false,
   t: key => key,
   windowDraggable: true,
 };
diff --git a/src/containers/WindowTopBar.js b/src/containers/WindowTopBar.js
index 82148be2f4..1fee8d051f 100644
--- a/src/containers/WindowTopBar.js
+++ b/src/containers/WindowTopBar.js
@@ -4,7 +4,7 @@ import { withTranslation } from 'react-i18next';
 import { withStyles } from '@material-ui/core';
 import { withPlugins } from '../extend/withPlugins';
 import * as actions from '../state/actions';
-import { getWindowConfig, isFocused } from '../state/selectors';
+import { getWindow, getWindowConfig, isFocused } from '../state/selectors';
 import { WindowTopBar } from '../components/WindowTopBar';
 
 /** mapStateToProps */
@@ -19,6 +19,7 @@ const mapStateToProps = (state, { windowId }) => {
     allowWindowSideBar: config.allowWindowSideBar,
     focused: isFocused(state, { windowId }),
     maximized: config.maximized,
+    sideBarOpen: (getWindow(state, { windowId }) || {}).sideBarOpen,
   };
 };
 
diff --git a/src/locales/de/translation.json b/src/locales/de/translation.json
index a484f06452..d360139a4e 100644
--- a/src/locales/de/translation.json
+++ b/src/locales/de/translation.json
@@ -55,6 +55,7 @@
     "fetchManifest": "Hinzufügen",
     "fullScreen": "Vollbild",
     "gallery": "Galerie",
+    "hideWindowSideBar": "Seitenleiste ausblenden",
     "hideZoomControls": "Zoomsteuerung verbergen",
     "iiif_homepage": "Über diese Ressource",
     "iiif_manifest": "IIIF-Manifest",
@@ -119,6 +120,7 @@
     "searchTitle": "Suche",
     "selectWorkspaceMenu": "Wählen Sie einen Arbeitsflächentyp",
     "showingNumAnnotations": "{{number}} Annotationen werden angezeigt",
+    "showWindowSideBar": "Seitenleiste einblenden",
     "showZoomControls": "Zoomsteuerung anzeigen",
     "sidebarPanelsNavigation": "Hilfsfensternavigation",
     "single": "Einzeln",
@@ -129,7 +131,7 @@
     "thumbnailList": "Miniaturansicht",
     "thumbnailNavigation": "Miniaturansicht",
     "thumbnails": "Miniaturansicht",
-    "toggleWindowSideBar": "Seitenleiste ein-/ausblenden",
+    "toggleWindowSideBar": "Seitenleiste umschalten",
     "tryAgain": "Wiederholen",
     "untitled": "[Unbenannt]",
     "view": "Ansicht",
diff --git a/src/locales/en/translation.json b/src/locales/en/translation.json
index 07dfbec7d2..097a866f34 100644
--- a/src/locales/en/translation.json
+++ b/src/locales/en/translation.json
@@ -57,6 +57,7 @@
     "fetchManifest": "Add",
     "fullScreen": "Full Screen",
     "gallery": "Gallery",
+    "hideWindowSideBar": "Hide sidebar",
     "hideZoomControls": "Hide zoom controls",
     "iiif_homepage": "About this resource",
     "iiif_manifest": "IIIF manifest",
@@ -123,6 +124,7 @@
     "selectWorkspaceMenu": "Select workspace type",
     "showingNumAnnotations": "Showing {{number}} annotations",
     "showCollection": "Show collection",
+    "showWindowSideBar": "Show sidebar",
     "showZoomControls": "Show zoom controls",
     "sidebarPanelsNavigation": "Sidebar panels navigation",
     "single": "Single",
@@ -133,7 +135,7 @@
     "thumbnailList": "Thumbnail list",
     "thumbnailNavigation": "Thumbnails",
     "thumbnails": "Thumbnails",
-    "toggleWindowSideBar": "Show / hide sidebar",
+    "toggleWindowSideBar": "Toggle sidebar",
     "totalCollections": "{{count}} collections",
     "totalManifests": "{{count}} manifests",
     "tryAgain": "Try again",