diff --git a/src/wp-admin/export.php b/src/wp-admin/export.php
index 7f416c4656..6efb7a7510 100644
--- a/src/wp-admin/export.php
+++ b/src/wp-admin/export.php
@@ -177,8 +177,13 @@ function export_date_options( $post_type = 'post' ) {
 		<label><span class="label-responsive"><?php _e( 'Authors:' ); ?></span>
 		<?php
 		$authors = $wpdb->get_col( "SELECT DISTINCT post_author FROM {$wpdb->posts} WHERE post_type = 'post'" );
-		wp_dropdown_users( array( 'include' => $authors, 'name' => 'post_author', 'multi' => true, 'show_option_all' => __('All') ) );
-		?>
+		wp_dropdown_users( array(
+			'include' => $authors,
+			'name' => 'post_author',
+			'multi' => true,
+			'show_option_all' => __( 'All' ),
+			'show' => 'display_name_with_login',
+		) ); ?>
 		</label>
 	</li>
 	<li>
@@ -214,8 +219,13 @@ function export_date_options( $post_type = 'post' ) {
 		<label><span class="label-responsive"><?php _e( 'Authors:' ); ?></span>
 		<?php
 		$authors = $wpdb->get_col( "SELECT DISTINCT post_author FROM {$wpdb->posts} WHERE post_type = 'page'" );
-		wp_dropdown_users( array( 'include' => $authors, 'name' => 'page_author', 'multi' => true, 'show_option_all' => __('All') ) );
-		?>
+		wp_dropdown_users( array(
+			'include' => $authors,
+			'name' => 'page_author',
+			'multi' => true,
+			'show_option_all' => __( 'All' ),
+			'show' => 'display_name_with_login',
+		) ); ?>
 		</label>
 	</li>
 	<li>
diff --git a/src/wp-admin/includes/ajax-actions.php b/src/wp-admin/includes/ajax-actions.php
index 58734452f9..47a1fb0eb6 100644
--- a/src/wp-admin/includes/ajax-actions.php
+++ b/src/wp-admin/includes/ajax-actions.php
@@ -289,7 +289,7 @@ function wp_ajax_autocomplete_user() {
 	foreach ( $users as $user ) {
 		$return[] = array(
 			/* translators: 1: user_login, 2: user_email */
-			'label' => sprintf( __( '%1$s (%2$s)' ), $user->user_login, $user->user_email ),
+			'label' => sprintf( _x( '%1$s (%2$s)', 'user autocomplete result' ), $user->user_login, $user->user_email ),
 			'value' => $user->$field,
 		);
 	}
diff --git a/src/wp-admin/includes/class-wp-posts-list-table.php b/src/wp-admin/includes/class-wp-posts-list-table.php
index d52ebc9832..8a1cd65d18 100644
--- a/src/wp-admin/includes/class-wp-posts-list-table.php
+++ b/src/wp-admin/includes/class-wp-posts-list-table.php
@@ -1335,7 +1335,8 @@ class WP_Posts_List_Table extends WP_List_Table {
 					'name' => 'post_author',
 					'class'=> 'authors',
 					'multi' => 1,
-					'echo' => 0
+					'echo' => 0,
+					'show' => 'display_name_with_login',
 				);
 				if ( $bulk )
 					$users_opt['show_option_none'] = __( '&mdash; No Change &mdash;' );
diff --git a/src/wp-admin/includes/meta-boxes.php b/src/wp-admin/includes/meta-boxes.php
index 1627b1f577..f52af1470e 100644
--- a/src/wp-admin/includes/meta-boxes.php
+++ b/src/wp-admin/includes/meta-boxes.php
@@ -742,7 +742,8 @@ function post_author_meta_box($post) {
 		'who' => 'authors',
 		'name' => 'post_author_override',
 		'selected' => empty($post->ID) ? $user_ID : $post->post_author,
-		'include_selected' => true
+		'include_selected' => true,
+		'show' => 'display_name_with_login',
 	) );
 }
 
diff --git a/src/wp-admin/users.php b/src/wp-admin/users.php
index cdf0d8b372..44d860ecfa 100644
--- a/src/wp-admin/users.php
+++ b/src/wp-admin/users.php
@@ -270,7 +270,11 @@ case 'delete':
 			<?php _e('Delete all content.'); ?></label></li>
 			<li><input type="radio" id="delete_option1" name="delete_option" value="reassign" />
 			<?php echo '<label for="delete_option1">' . __( 'Attribute all content to:' ) . '</label> ';
-			wp_dropdown_users( array( 'name' => 'reassign_user', 'exclude' => array_diff( $userids, array($current_user->ID) ) ) ); ?></li>
+			wp_dropdown_users( array(
+				'name' => 'reassign_user',
+				'exclude' => array_diff( $userids, array( $current_user->ID ) ),
+				'show' => 'display_name_with_login',
+			) ); ?></li>
 		</ul></fieldset>
 	<?php endif;
 	/**
diff --git a/src/wp-includes/user.php b/src/wp-includes/user.php
index 45da472f12..f14fa486a7 100644
--- a/src/wp-includes/user.php
+++ b/src/wp-includes/user.php
@@ -870,6 +870,7 @@ function setup_userdata($for_user_id = '') {
  * The available arguments are as follows:
  *
  * @since 2.3.0
+ * @since 4.5.0 Added the 'display_name_with_login' value for 'show'.
  *
  * @global int  $blog_id
  *
@@ -896,9 +897,11 @@ function setup_userdata($for_user_id = '') {
  *                                                 Default empty.
  *     @type bool|int     $multi                   Whether to skip the ID attribute on the 'select' element.
  *                                                 Accepts 1|true or 0|false. Default 0|false.
- *     @type string       $show                    User table column to display. If the selected item is empty
+ *     @type string       $show                    User data to display. If the selected item is empty
  *                                                 then the 'user_login' will be displayed in parentheses.
- *                                                 Accepts user fields. Default 'display_name'.
+ *                                                 Accepts any user field, or 'display_name_with_login' to show
+ *                                                 the display name with user_login in parentheses.
+ *                                                 Default 'display_name'.
  *     @type int|bool     $echo                    Whether to echo or return the drop-down. Accepts 1|true (echo)
  *                                                 or 0|false (return). Default 1|true.
  *     @type int          $selected                Which user ID should be selected. Default 0.
@@ -927,14 +930,24 @@ function wp_dropdown_users( $args = '' ) {
 	$defaults['selected'] = is_author() ? get_query_var( 'author' ) : 0;
 
 	$r = wp_parse_args( $args, $defaults );
-	$show = $r['show'];
+
+	$query_args = wp_array_slice_assoc( $r, array( 'blog_id', 'include', 'exclude', 'orderby', 'order', 'who' ) );
+
+	$fields = array( 'ID', 'user_login' );
+
+	$show = ! empty( $r['show'] ) ? $r['show'] : 'display_name';
+	if ( 'display_name_with_login' === $show ) {
+		$fields[] = 'display_name';
+	} else {
+		$fields[] = $show;
+	}
+
+	$query_args['fields'] = $fields;
+
 	$show_option_all = $r['show_option_all'];
 	$show_option_none = $r['show_option_none'];
 	$option_none_value = $r['option_none_value'];
 
-	$query_args = wp_array_slice_assoc( $r, array( 'blog_id', 'include', 'exclude', 'orderby', 'order', 'who' ) );
-	$query_args['fields'] = array( 'ID', 'user_login', $show );
-
 	/**
 	 * Filter the query arguments for the user drop-down.
 	 *
@@ -966,21 +979,32 @@ function wp_dropdown_users( $args = '' ) {
 			$output .= "\t<option value='" . esc_attr( $option_none_value ) . "'$_selected>$show_option_none</option>\n";
 		}
 
-		$found_selected = false;
-		foreach ( (array) $users as $user ) {
-			$user->ID = (int) $user->ID;
-			$_selected = selected( $user->ID, $r['selected'], false );
-			if ( $_selected ) {
-				$found_selected = true;
+		if ( $r['include_selected'] && ( $r['selected'] > 0 ) ) {
+			$found_selected = false;
+			$r['selected'] = (int) $r['selected'];
+			foreach ( (array) $users as $user ) {
+				$user->ID = (int) $user->ID;
+				if ( $user->ID === $r['selected'] ) {
+					$found_selected = true;
+				}
+			}
+
+			if ( ! $found_selected ) {
+				$users[] = get_userdata( $r['selected'] );
 			}
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
-			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}
 
-		if ( $r['include_selected'] && ! $found_selected && ( $r['selected'] > 0 ) ) {
-			$user = get_userdata( $r['selected'] );
+		foreach ( (array) $users as $user ) {
+			if ( 'display_name_with_login' === $show ) {
+				/* translators: 1: display name, 2: user_login */
+				$display = sprintf( _x( '%1$s (%2$s)', 'user dropdown' ), $user->display_name, $user->user_login );
+			} elseif ( ! empty( $user->$show ) ) {
+				$display = $user->$show;
+			} else {
+				$display = '(' . $user->user_login . ')';
+			}
+
 			$_selected = selected( $user->ID, $r['selected'], false );
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
 			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}
 
diff --git a/tests/phpunit/tests/user/wpDropdownUsers.php b/tests/phpunit/tests/user/wpDropdownUsers.php
new file mode 100644
index 0000000000..844c9532ed
--- /dev/null
+++ b/tests/phpunit/tests/user/wpDropdownUsers.php
@@ -0,0 +1,113 @@
+<?php
+
+/**
+ * Test functions in wp-includes/user.php
+ *
+ * @group user
+ */
+class Tests_User_WpDropdownUsers extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 31251
+	 */
+	public function test_default_value_of_show_should_be_display_name() {
+
+		// create a user with a different display_name
+		$u = $this->factory->user->create( array(
+			'user_login'   => 'foo',
+			'display_name' => 'Foo Person'
+		) );
+
+		$found = wp_dropdown_users( array(
+			'echo' => false
+		) );
+
+		$expected = "<option value='$u'>Foo Person</option>";
+
+		$this->assertContains( $expected, $found );
+	}
+
+	/**
+	 * @ticket 31251
+	 */
+	public function test_show_should_display_display_name_show_is_specified_as_empty() {
+
+		// create a user with a different display_name
+		$u = $this->factory->user->create( array(
+			'user_login'   => 'foo',
+			'display_name' => 'Foo Person'
+		) );
+
+		// Get the result of a non-default, but acceptable input for 'show' parameter to wp_dropdown_users().
+		$found = wp_dropdown_users( array(
+			'echo' => false,
+			'show' => ''
+		) );
+
+		$expected = "<option value='$u'>Foo Person</option>";
+
+		$this->assertContains( $expected, $found );
+	}
+
+	/**
+	 * @ticket 31251
+	 */
+	public function test_show_should_display_user_property_when_the_value_of_show_is_a_valid_user_property() {
+
+		// create a user with a different display_name
+		$u = $this->factory->user->create( array(
+			'user_login'   => 'foo',
+			'display_name' => 'Foo Person'
+		) );
+
+		// Get the result of a non-default, but acceptable input for 'show' parameter to wp_dropdown_users().
+		$found = wp_dropdown_users( array(
+			'echo' => false,
+			'show' => 'user_login'
+		) );
+
+		$expected = "<option value='$u'>foo</option>";
+
+		$this->assertContains( $expected, $found );
+	}
+
+	/**
+	 * @ticket 31251
+	 */
+	public function test_show_display_name_with_login() {
+
+		// create a user with a different display_name
+		$u = $this->factory->user->create( array(
+			'user_login'   => 'foo',
+			'display_name' => 'Foo Person'
+		) );
+
+		// Get the result of a non-default, but acceptable input for 'show' parameter to wp_dropdown_users().
+		$found = wp_dropdown_users( array(
+			'echo' => false,
+			'show' => 'display_name_with_login'
+		) );
+
+		$expected = "<option value='$u'>Foo Person (foo)</option>";
+
+		$this->assertContains( $expected, $found );
+	}
+
+	/**
+	 * @ticket 31251
+	 */
+	public function test_include_selected() {
+		$users = self::factory()->user->create_many( 2 );
+
+		$found = wp_dropdown_users( array(
+			'echo' => false,
+			'include' => $users[0],
+			'selected' => $users[1],
+			'include_selected' => true,
+			'show' => 'user_login',
+		) );
+
+		$user1 = get_userdata( $users[1] );
+		$this->assertContains( $user1->user_login, $found );
+	}
+}