diff --git a/components/select.inc b/components/select.inc
index eb0fb69..5a3c9bd 100644
--- a/components/select.inc
+++ b/components/select.inc
@@ -166,7 +166,7 @@ function _webform_edit_select($component) {
     '#type' => 'checkbox',
     '#title' => t('Listbox'),
     '#default_value' => $component['extra']['aslist'],
-    '#description' => t('Check this option if you want the select component to be of listbox type instead of radio buttons or checkboxes.'),
+    '#description' => t('Check this option if you want the select component to be displayed as a select list box instead of radio buttons or checkboxes. Option groups (nested options) are only supported with listbox components.'),
     '#parents' => array('extra', 'aslist'),
   );
   $form['display']['optrand'] = array(
@@ -232,6 +232,8 @@ function _webform_edit_validate_select($element, &$form_state) {
       form_error($element, t('Options within the select list must be unique. The following keys have been used multiple times:') . theme('item_list', array('items' => $duplicate_keys)));
     }
 
+    // Set the listbox option if needed.
+    _webform_edit_validate_set_aslist($existing_keys, $form_state);
   }
 
   return TRUE;
@@ -252,6 +254,9 @@ function _webform_edit_validate_options($element, &$form_state) {
     $form_state['values']['extra']['multiple'] = $element_options['multiple'];
     $form_state['values']['extra']['custom_keys'] = $element_options['custom_keys'];
     $form_state['values']['value'] = is_array($element_options['default_value']) ? implode(', ', $element_options['default_value']) : $element_options['default_value'];
+
+    // Set the listbox option if needed.
+    _webform_edit_validate_set_aslist($element_options['options'], $form_state);
   }
   // Options saved for grid components.
   else {
@@ -260,6 +265,21 @@ function _webform_edit_validate_options($element, &$form_state) {
 }
 
 /**
+ * Ensure "aslist" is used for option groups. Called from options validations.
+ */
+function _webform_edit_validate_set_aslist($options, &$form_state) {
+  if (empty($form_state['values']['extra']['aslist']) && !empty($options)) {
+    foreach ($options as $option) {
+      if (is_array($option)) {
+        $form_state['values']['extra']['aslist'] = 1;
+        drupal_set_message(t('The component %name has automatically been set to display as a listbox in order to support option groups.', array('%name' => $form_state['values']['name'])), 'warning');
+        break;
+      }
+    }
+  }
+}
+
+/**
  * Implements _webform_render_component().
  */
 function _webform_render_select($component, $value = NULL, $filter = TRUE) {