Hi malcolm76, you can re-open the Bookmarks Sidebar using any of these methods: * Command+b (assuming the current page doesn't intercept it) * on the menu bar: View > Sidebar > Bookmarks * using the Bookmarks menu button on the main toolbar: View Bookmarks Sidebar * using the optional Sidebars button you can add to the toolbar or graphical menu: see [[Customize Firefox controls, buttons and toolbars]] I'm not sure what causes it to open automatically, but perhaps leaving it open when you quit Firefox will save that status?