diff --git a/term_reference_tree.js b/term_reference_tree.js
index 61e5ed9..7cf7229 100644
--- a/term_reference_tree.js
+++ b/term_reference_tree.js
@@ -11,6 +11,38 @@ Drupal.behaviors.termReferenceTree = {
       $(this).siblings('ul').slideToggle('fast');
     });
 
+    // Search filtering.
+    $('.term-reference-tree-filter', context).once('term-reference-tree-filter').bind('keyup click', function() {
+      var searchTerms = $(this).val().toLowerCase();
+      var tree = $(this).closest('.term-reference-tree').children('ul');
+      if (searchTerms.length > 2) {
+        $(tree).find('li').each(function() {
+          var hasMatch = $(this).text().toLowerCase().indexOf(searchTerms) > 0;
+          var button = $(this).children('.term-reference-tree-button');
+          if (hasMatch) {
+            $(button).removeClass('term-reference-tree-collapsed');
+            $(button).siblings('ul').slideDown('fast');
+          }
+          else {
+            if (!$(this).find('input:checkbox:checked').length) {
+              $(button).addClass('term-reference-tree-collapsed');
+              $(button).siblings('ul').slideUp('fast');
+            }
+          }
+        });
+      }
+      else {
+        var unselected = $(tree).find('li').filter(function() {
+          return !$(this).find('input:checkbox:checked').length;
+        });
+        $(unselected).each(function() {
+          var button = $(this).children('.term-reference-tree-button');
+          $(button).addClass('term-reference-tree-collapsed');
+          $(button).siblings('ul').slideUp('fast');
+        });
+      }
+    })
+
     // An expand all button (unimplemented)
     /*
     $('.expandbutton').click(function() {
diff --git a/term_reference_tree.widget.inc b/term_reference_tree.widget.inc
index 1685a43..7437beb 100644
--- a/term_reference_tree.widget.inc
+++ b/term_reference_tree.widget.inc
@@ -22,6 +22,7 @@ function term_reference_tree_field_widget_info() {
         'token_display' => '',
         'parent_term_id' => '',
         'max_depth' => '',
+        'search' => 0,
       ),
     ),
   );
@@ -142,6 +143,12 @@ function term_reference_tree_field_widget_settings_form($field, $instance) {
       '#size' => 8,
       '#return_value' => 1,
     );
+
+    $form['search'] = array(
+      '#type' => 'checkbox',
+      '#title' => t('Display a search field to filter results'),
+      '#default_value' => $settings['search'],
+    );
   }
 
   return $form;
@@ -526,6 +533,15 @@ function term_reference_tree_field_widget_form(&$form, &$form_state, $field, $in
     '#properties' => $properties,
   );
 
+  $element['filter'] = array(
+    '#type' => module_exists('elements') ? 'searchfield' : 'textfield',
+    '#title' => t('Filter terms'),
+    '#size' => 30,
+    '#weight' => -1,
+    '#attributes' => array('class' => array('term-reference-tree-filter')),
+    '#access' => $settings['search'],
+  );
+
   return $element;
 }