Index: wp-content/plugins/handbook/handbook.php
===================================================================
--- wp-content/plugins/handbook/handbook.php	(revision 1930)
+++ wp-content/plugins/handbook/handbook.php	(working copy)
@@ -30,6 +30,7 @@
 		}
 
 		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue_styles' ) );
+		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue_scripts' ) );
 	}
 
 	static public function enqueue_styles() {
@@ -36,6 +37,10 @@
 		wp_enqueue_style( 'wporg-handbook-css', plugins_url( '/stylesheets/callout-boxes.css', __FILE__ ), array(), '20150507' );
 	}
 
+	static public function enqueue_scripts() {
+		wp_enqueue_script( 'wporg-handbook', plugins_url( '/scripts/handbook.js', __FILE__ ), array( 'jquery' ), '20150930' );
+	}
+
 }
 
 add_action( 'after_setup_theme', array( 'WPorg_Handbook_Init', 'init' ) );
@@ -235,4 +240,4 @@
 		}
 	}
 
-}
\ No newline at end of file
+}
Index: wp-content/plugins/handbook/scripts/handbook.js
===================================================================
--- wp-content/plugins/handbook/scripts/handbook.js	(revision 0)
+++ wp-content/plugins/handbook/scripts/handbook.js	(working copy)
@@ -0,0 +1,34 @@
+/**
+ * Enables toggling visibility of all the chapters in the Handbook Chapter widget.
+ *
+ * @since ???
+ */
+var toggleChapters = function () {
+	/**
+	 * The Handbook Chapter widget title element.
+	 *
+	 * @type {NodeList}
+	 */
+	var chapterWidgetHeading = document.querySelectorAll( '.widget_wporg_handbook_pages .widgettitle' );
+
+	/*
+	 * Bind to the touch and click events to make it useful on both mobile and desktop.
+	 * Since 'click' is the last event in the chain, we use preventDefault() to stop the
+	 * touch event from continuing and triggering a "ghost click".
+	 *
+	 * @link http://www.html5rocks.com/en/mobile/touchandmouse/
+	 */
+	jQuery( chapterWidgetHeading ).bind( 'touchstart click', function ( e ) {
+		e.preventDefault();
+		jQuery( this ).next( '.menu-table-of-contents-container' ).toggle();
+	} );
+};
+
+// Layout changes the widget at 700px, so we don't want to enable toggling above that.
+// @todo Check on window resize, rather than just on page loading
+jQuery( document ).ready( function() {
+	if ( 700 >= parseInt( jQuery( window ).width(), 10 ) ) {
+		toggleChapters();
+	}
+});
+