Index: src/wp-admin/js/customize-widgets.js
===================================================================
--- src/wp-admin/js/customize-widgets.js	(revision 33587)
+++ src/wp-admin/js/customize-widgets.js	(working copy)
@@ -1644,11 +1644,7 @@
 			/**
 			 * Keyboard-accessible reordering
 			 */
-			this.container.find( '.reorder-toggle' ).on( 'click keydown', function( event ) {
-				if ( event.type === 'keydown' && ! ( event.which === 13 || event.which === 32 ) ) { // Enter or Spacebar
-					return;
-				}
-
+			this.container.find( '.reorder-toggle' ).on( 'click', function() {
 				self.toggleReordering( ! self.isReordering );
 			} );
 		},
@@ -1659,18 +1655,16 @@
 		_setupAddition: function() {
 			var self = this;

-			this.container.find( '.add-new-widget' ).on( 'click keydown', function( event ) {
-				if ( event.type === 'keydown' && ! ( event.which === 13 || event.which === 32 ) ) { // Enter or Spacebar
-					return;
-				}
-
+			this.container.find( '.add-new-widget' ).on( 'click', function() {
 				if ( self.$sectionContent.hasClass( 'reordering' ) ) {
 					return;
 				}

 				if ( ! $( 'body' ).hasClass( 'adding-widget' ) ) {
+					$( this ).attr( 'aria-expanded', 'true' );
 					api.Widgets.availableWidgetsPanel.open( self );
 				} else {
+					$( this ).attr( 'aria-expanded', 'false' );
 					api.Widgets.availableWidgetsPanel.close();
 				}
 			} );
@@ -1724,6 +1718,9 @@
 		 * @todo We should have a reordering state instead and rename this to onChangeReordering
 		 */
 		toggleReordering: function( showOrHide ) {
+			var addNewWidgetBtn = this.$sectionContent.find( '.add-new-widget' ),
+				reorderBtn = this.container.find( '.reorder-toggle' );
+
 			showOrHide = Boolean( showOrHide );

 			if ( showOrHide === this.$sectionContent.hasClass( 'reordering' ) ) {
@@ -1738,10 +1735,13 @@
 					formControl.collapse();
 				} );

-				this.$sectionContent.find( '.first-widget .move-widget' ).focus();
-				this.$sectionContent.find( '.add-new-widget' ).prop( 'tabIndex', -1 );
+				addNewWidgetBtn.attr({ 'tabindex': '-1', 'aria-hidden': 'true' });
+				reorderBtn.attr( 'aria-label', l10n.reorderLabelOff );
+				wp.a11y.speak( l10n.reorderModeOn );
 			} else {
-				this.$sectionContent.find( '.add-new-widget' ).prop( 'tabIndex', 0 );
+				addNewWidgetBtn.removeAttr( 'tabindex aria-hidden' );
+				reorderBtn.attr( 'aria-label', l10n.reorderLabelOn );
+				wp.a11y.speak( l10n.reorderModeOff );
 			}
 		},

Index: src/wp-includes/class-wp-customize-control.php
===================================================================
--- src/wp-includes/class-wp-customize-control.php	(revision 33587)
+++ src/wp-includes/class-wp-customize-control.php	(working copy)
@@ -1456,15 +1456,16 @@
 	 * @access public
 	 */
 	public function render_content() {
+		$id = 'reorder-widgets-desc-' . str_replace( '[', '-', str_replace( ']', '', $this->id ) );
 		?>
-		<span class="button-secondary add-new-widget" tabindex="0">
+		<button type="button" class="button-secondary add-new-widget" aria-label="<?php esc_attr_e( 'Add or remove widgets' ); ?>" aria-expanded="false" aria-controls="available-widgets">
 			<?php _e( 'Add a Widget' ); ?>
-		</span>
-
-		<span class="reorder-toggle" tabindex="0">
+		</button>
+		<button type="button" class="not-a-button reorder-toggle" aria-label="<?php esc_attr_e( 'Reorder' ); ?>" aria-describedby="<?php echo esc_attr( $id ); ?>">
 			<span class="reorder"><?php _ex( 'Reorder', 'Reorder widgets in Customizer' ); ?></span>
 			<span class="reorder-done"><?php _ex( 'Done', 'Cancel reordering widgets in Customizer' ); ?></span>
-		</span>
+		</button>
+		<p class="screen-reader-text" id="<?php echo esc_attr( $id ); ?>"><?php _e( 'When in reorder mode, additional controls to reorder widgets will be available in the widgets list above.' ); ?></p>
 		<?php
 	}

Index: src/wp-includes/class-wp-customize-widgets.php
===================================================================
--- src/wp-includes/class-wp-customize-widgets.php	(revision 33587)
+++ src/wp-includes/class-wp-customize-widgets.php	(working copy)
@@ -655,6 +655,10 @@
 				'error'            => __( 'An error has occurred. Please reload the page and try again.' ),
 				'widgetMovedUp'    => __( 'Widget moved up' ),
 				'widgetMovedDown'  => __( 'Widget moved down' ),
+				'reorderModeOn'    => __( 'Reorder mode enabled' ),
+				'reorderModeOff'   => __( 'Reorder mode closed' ),
+				'reorderLabelOn'   => esc_attr__( 'Reorder' ),
+				'reorderLabelOff'  => esc_attr__( 'Close reorder mode' ),
 			),
 			'tpl' => array(
 				'widgetReorderNav' => $widget_reorder_nav_tpl,