Index: wp-content/themes/twentyfourteen/header.php
===================================================================
--- wp-content/themes/twentyfourteen/header.php	(revision 31784)
+++ wp-content/themes/twentyfourteen/header.php	(working copy)
@@ -45,7 +45,7 @@
 			<h1 class="site-title"><a href="<?php echo esc_url( home_url( '/' ) ); ?>" rel="home"><?php bloginfo( 'name' ); ?></a></h1>
 
 			<div class="search-toggle">
-				<a href="#search-container" class="screen-reader-text"><?php _e( 'Search', 'twentyfourteen' ); ?></a>
+				<a href="#search-container" class="screen-reader-text" aria-expanded="false" aria-controls="search-container"><?php _e( 'Search', 'twentyfourteen' ); ?></a>
 			</div>
 
 			<nav id="primary-navigation" class="site-navigation primary-navigation" role="navigation">
Index: wp-content/themes/twentyfourteen/js/functions.js
===================================================================
--- wp-content/themes/twentyfourteen/js/functions.js	(revision 31784)
+++ wp-content/themes/twentyfourteen/js/functions.js	(working copy)
@@ -69,10 +69,18 @@
 		// Search toggle.
 		$( '.search-toggle' ).on( 'click.twentyfourteen', function( event ) {
 			var that    = $( this ),
-				wrapper = $( '.search-box-wrapper' );
+				wrapper = $( '#search-container' );
 
 			that.toggleClass( 'active' );
 			wrapper.toggleClass( 'hide' );
+			
+			if ( that.hasClass( 'active' ) ) {
+				that.attr( 'aria-expanded', 'true' );
+				wrapper.attr( 'aria-expanded', 'true' );
+			} else {
+				that.attr( 'aria-expanded', 'false' );
+				wrapper.attr( 'aria-expanded', 'false' );
+			}
 
 			if ( that.is( '.active' ) || $( '.search-toggle .screen-reader-text' )[0] === event.target ) {
 				wrapper.find( '.search-field' ).focus();