diff --git a/themes/wporg-5ftf/footer.php b/themes/wporg-5ftf/footer.php
index f50caea..dec6ba4 100644
--- a/themes/wporg-5ftf/footer.php
+++ b/themes/wporg-5ftf/footer.php
@@ -6,4 +6,10 @@ namespace WordPressDotOrg\FiveForTheFuture\Theme;
 
 	</div><!-- #content -->
 
-<?php require WPORGPATH . 'footer.php';
+<?php
+
+if ( FEATURE_2021_GLOBAL_HEADER_FOOTER ) {
+	echo do_blocks( '<!-- wp:wporg/global-footer /-->' );
+} else {
+	require WPORGPATH . 'footer.php';
+}
diff --git a/themes/wporg-5ftf/functions.php b/themes/wporg-5ftf/functions.php
index 76fd286..c2112fc 100644
--- a/themes/wporg-5ftf/functions.php
+++ b/themes/wporg-5ftf/functions.php
@@ -2,6 +2,11 @@
 
 namespace WordPressDotOrg\FiveForTheFuture\Theme;
 
+// Temporary for local environments. Remove this when the new header launches.
+// See https://github.com/WordPress/wporg-mu-plugins/issues/38
+if ( ! defined( 'FEATURE_2021_GLOBAL_HEADER_FOOTER' ) ) {
+	define( 'FEATURE_2021_GLOBAL_HEADER_FOOTER', false );
+}
 
 /**
  * Sets up theme defaults and registers support for various WordPress features.
diff --git a/themes/wporg-5ftf/header.php b/themes/wporg-5ftf/header.php
index a7c7e67..6a7b760 100644
--- a/themes/wporg-5ftf/header.php
+++ b/themes/wporg-5ftf/header.php
@@ -2,17 +2,21 @@
 
 namespace WordPressDotOrg\FiveForTheFuture\Theme;
 
-global $wporg_global_header_options;
-$GLOBALS['pagetitle'] = wp_get_document_title();
+if ( FEATURE_2021_GLOBAL_HEADER_FOOTER ) {
+	echo do_blocks( '<!-- wp:wporg/global-header /-->' );
+} else {
+	global $wporg_global_header_options;
+	$GLOBALS['pagetitle'] = wp_get_document_title();
 
-if ( ! isset( $wporg_global_header_options['in_wrapper'] ) ) {
-	$wporg_global_header_options['in_wrapper'] = '';
+	if ( ! isset( $wporg_global_header_options['in_wrapper'] ) ) {
+		$wporg_global_header_options['in_wrapper'] = '';
+	}
+
+	$wporg_global_header_options['in_wrapper'] .= '<a class="skip-link screen-reader-text" href="#main">' . esc_html__( 'Skip to content', 'wporg-5ftf' ) . '</a>';
+
+	require WPORGPATH . 'header.php';
 }
 
-$wporg_global_header_options['in_wrapper'] .= '<a class="skip-link screen-reader-text" href="#main">' . esc_html__( 'Skip to content', 'wporg-5ftf' ) . '</a>';
-
-require WPORGPATH . 'header.php';
-
 ?>
 
 <div id="page" class="site">