diff --git a/emmental/header/__init__.py b/emmental/header/__init__.py
index 25528a0..1248d0d 100644
--- a/emmental/header/__init__.py
+++ b/emmental/header/__init__.py
@@ -34,6 +34,7 @@ class Header(Gtk.HeaderBar):
     sql = GObject.Property(type=db.Connection)
     title = GObject.Property(type=str)
     subtitle = GObject.Property(type=str)
+    show_sidebar = GObject.Property(type=bool, default=False)
     bg_enabled = GObject.Property(type=bool, default=False)
     bg_volume = GObject.Property(type=float, default=0.5)
     rg_enabled = GObject.Property(type=bool, default=False)
@@ -43,6 +44,8 @@ class Header(Gtk.HeaderBar):
     def __init__(self, sql: db.Connection, title: str):
         """Initialize the HeaderBar."""
         super().__init__(title=title, subtitle=SUBTITLE, sql=sql)
+        icon = "sidebar-show-symbolic"
+        self._show_sidebar = Gtk.ToggleButton(icon_name=icon, has_frame=False)
         self._open = open.Button()
         self._title = Adw.WindowTitle(title=self.title, subtitle=self.subtitle,
                                       tooltip_text=gsetup.env_string())
@@ -68,6 +71,8 @@ class Header(Gtk.HeaderBar):
 
         self.bind_property("title", self._title, "title")
         self.bind_property("subtitle", self._title, "subtitle")
+        self.bind_property("show-sidebar", self._show_sidebar, "active",
+                           GObject.BindingFlags.BIDIRECTIONAL)
         self.bind_property("bg-enabled", self._background, "enabled",
                            GObject.BindingFlags.BIDIRECTIONAL)
         self.bind_property("bg-volume", self._background, "volume",
@@ -79,6 +84,7 @@ class Header(Gtk.HeaderBar):
         self.bind_property("volume", self._volume, "volume",
                            GObject.BindingFlags.BIDIRECTIONAL)
 
+        self.pack_start(self._show_sidebar)
         self.pack_start(self._open)
         if __debug__:
             self._window = settings.Window(sql)
diff --git a/tests/header/test_header.py b/tests/header/test_header.py
index 65eb268..1e5c4ac 100644
--- a/tests/header/test_header.py
+++ b/tests/header/test_header.py
@@ -36,6 +36,21 @@ class TestHeader(tests.util.TestCase):
         self.assertEqual(self.header._title.get_tooltip_text(),
                          emmental.gsetup.env_string())
 
+    def test_show_sidebar(self):
+        """Check that the show sidebar button works as expected."""
+        self.assertIsInstance(self.header._show_sidebar, Gtk.ToggleButton)
+        self.assertEqual(self.header._show_sidebar.props.icon_name,
+                         "sidebar-show-symbolic")
+        self.assertFalse(self.header._show_sidebar.props.has_frame)
+        self.assertFalse(self.header._show_sidebar.props.active)
+
+        self.assertFalse(self.header.show_sidebar)
+        self.header.show_sidebar = True
+        self.assertTrue(self.header._show_sidebar.props.active)
+
+        self.header._show_sidebar.props.active = False
+        self.assertFalse(self.header.show_sidebar)
+
     def test_open(self):
         """Check that the Open button works as expected."""
         self.assertIsInstance(self.header._open, emmental.header.open.Button)