diff --git a/includes/Core/Admin_Bar/Admin_Bar.php b/includes/Core/Admin_Bar/Admin_Bar.php
index 063f2a74bfe..637e3d14505 100644
--- a/includes/Core/Admin_Bar/Admin_Bar.php
+++ b/includes/Core/Admin_Bar/Admin_Bar.php
@@ -82,7 +82,11 @@ function( $wp_admin_bar ) {
 			$this->assets->enqueue_asset( 'googlesitekit_adminbar_css' );
 
 			if ( $this->context->is_amp() ) {
-				return;
+				if ( ! $this->is_amp_dev_mode() ) {
+					// AMP Dev Mode support was added in v1.4, and if it is not enabled then short-circuit since scripts will be invalid.
+					return;
+				}
+				add_filter( 'amp_dev_mode_element_xpaths', array( $this, 'add_amp_dev_mode' ) );
 			}
 
 			// Enqueue scripts.
@@ -92,6 +96,20 @@ function( $wp_admin_bar ) {
 		add_action( 'wp_enqueue_scripts', $admin_bar_callback, 40 );
 	}
 
+	/**
+	 * Add data-ampdevmode attributes to the elements that need it.
+	 *
+	 * @see \Google\Site_Kit\Core\Assets\Assets::get_assets() The 'googlesitekit' string is added to all inline scripts.
+	 * @see \Google\Site_Kit\Core\Assets\Assets::add_amp_dev_mode_attributes() The data-ampdevmode attribute is added to registered scripts/styles here.
+	 *
+	 * @param string[] $xpath_queries XPath queries for elements that should get the data-ampdevmode attribute.
+	 * @return string[] XPath queries.
+	 */
+	public function add_amp_dev_mode( $xpath_queries ) {
+		$xpath_queries[] = '//script[ contains( text(), "googlesitekit" ) ]';
+		return $xpath_queries;
+	}
+
 	/**
 	 * Render the Adminbar button.
 	 *
@@ -113,7 +131,7 @@ private function add_menu_button( $wp_admin_bar ) {
 			),
 		);
 
-		if ( $this->context->is_amp() ) {
+		if ( $this->context->is_amp() && ! $this->is_amp_dev_mode() ) {
 			$post = get_post();
 			if ( ! $post || ! current_user_can( 'edit_post', $post->ID ) ) {
 				return;
@@ -215,6 +233,19 @@ private function is_admin_post_screen() {
 		return true;
 	}
 
+	/**
+	 * Checks whether AMP dev mode is enabled.
+	 *
+	 * This is only relevant if the current context is AMP.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @return bool True if AMP dev mode is enabled, false otherwise.
+	 */
+	private function is_amp_dev_mode() {
+		return function_exists( 'amp_is_dev_mode' ) && amp_is_dev_mode();
+	}
+
 	/**
 	 * Return the Adminbar content markup.
 	 *
diff --git a/includes/Core/Assets/Assets.php b/includes/Core/Assets/Assets.php
index d477ddf2885..8f0bfc2173b 100644
--- a/includes/Core/Assets/Assets.php
+++ b/includes/Core/Assets/Assets.php
@@ -230,6 +230,41 @@ private function register_assets() {
 		foreach ( $assets as $asset ) {
 			$asset->register();
 		}
+
+		$this->add_amp_dev_mode_attributes( $assets );
+	}
+
+	/**
+	 * Add data-ampdevmode attributes to assets.
+	 *
+	 * @todo What about dependencies?
+	 *
+	 * @param Asset[] $assets Assets.
+	 */
+	private function add_amp_dev_mode_attributes( $assets ) {
+		add_filter(
+			'script_loader_tag',
+			function ( $tag, $handle ) use ( $assets ) {
+				if ( $this->context->is_amp() && isset( $assets[ $handle ] ) && $assets[ $handle ] instanceof Script ) {
+					$tag = preg_replace( '/(?<=<script)(?=\s|>)/i', ' data-ampdevmode', $tag );
+				}
+				return $tag;
+			},
+			10,
+			2
+		);
+
+		add_filter(
+			'style_loader_tag',
+			function ( $tag, $handle ) use ( $assets ) {
+				if ( $this->context->is_amp() && isset( $assets[ $handle ] ) && $assets[ $handle ] instanceof Stylesheet ) {
+					$tag = preg_replace( '/(?<=<link)(?=\s|>)/i', ' data-ampdevmode', $tag );
+				}
+				return $tag;
+			},
+			10,
+			2
+		);
 	}
 
 	/**
@@ -248,7 +283,7 @@ private function enqueue_minimal_admin_script() {
 	 *
 	 * @since 1.0.0
 	 *
-	 * @return array Associative array of asset $handle => $instance pairs.
+	 * @return Asset[] Associative array of asset $handle => $instance pairs.
 	 */
 	private function get_assets() {
 		if ( $this->assets ) {
@@ -280,7 +315,7 @@ private function get_assets() {
 					'dependencies'  => array( 'sitekit-vendor' ),
 					'post_register' => function( $handle ) use ( $base_url ) {
 						$url_polyfill = (
-							'( typeof URL === \'function\') || ' .
+							'/*googlesitekit*/ ( typeof URL === \'function\') || ' .
 							'document.write( \'<script src="' . // phpcs:ignore WordPress.WP.EnqueuedResources.NonEnqueuedScript
 							$base_url . 'js/externals/wp-polyfill-url.js' .
 							'"></scr\' + \'ipt>\' );'
@@ -630,10 +665,10 @@ private function get_external_assets() {
 				'lodash',
 				array(
 					'src'           => $base_url . 'vendor/lodash' . $suffix . '.js',
-					'version'       => '4.17.11',
+					'version'       => '4.17.15',
 					'fallback'      => true,
 					'post_register' => function( $handle ) {
-						wp_add_inline_script( $handle, 'window.lodash = window.lodash || _.noConflict(); window.lodash_load = true;' );
+						wp_add_inline_script( $handle, '/*googlesitekit*/ window.lodash = window.lodash || _.noConflict(); window.lodash_load = true;' );
 					},
 				)
 			),
@@ -649,7 +684,7 @@ private function get_external_assets() {
 				'react',
 				array(
 					'src'      => $base_url . 'vendor/react' . $react_suffix . '.js',
-					'version'  => '16.8.5',
+					'version'  => '16.11.0',
 					'fallback' => true,
 				)
 			),
@@ -657,7 +692,7 @@ private function get_external_assets() {
 				'react-dom',
 				array(
 					'src'      => $base_url . 'vendor/react-dom' . $react_suffix . '.js',
-					'version'  => '16.8.5',
+					'version'  => '16.11.0',
 					'fallback' => true,
 				)
 			),
@@ -675,7 +710,7 @@ private function get_external_assets() {
 							'window.FormData && window.FormData.prototype.keys'      => $base_url . 'js/externals/wp-polyfill-formdata.js', // phpcs:ignore WordPress.Arrays.MultipleStatementAlignment
 							'Element.prototype.matches && Element.prototype.closest' => $base_url . 'js/externals/wp-polyfill-element-closest.js', // phpcs:ignore WordPress.Arrays.MultipleStatementAlignment
 						);
-						$polyfill_scripts = '';
+						$polyfill_scripts = '/*googlesitekit*/';
 						foreach ( $inline_polyfill_tests as $test => $script ) { // phpcs:ignore Generic.WhiteSpace.ScopeIndent.IncorrectExact
 							$polyfill_scripts .= (
 								'( ' . $test . ' ) || ' .
@@ -688,11 +723,27 @@ private function get_external_assets() {
 					},
 				)
 			),
+			new Script(
+				'wp-escape-html',
+				array(
+					'src'      => $base_url . 'js/externals/escapeHtml.js',
+					'version'  => '1.5.1',
+					'fallback' => true,
+				)
+			),
+			new Script(
+				'wp-is-shallow-equal',
+				array(
+					'src'      => $base_url . 'js/externals/isShallowEqual.js',
+					'version'  => '1.6.1',
+					'fallback' => true,
+				)
+			),
 			new Script(
 				'wp-hooks',
 				array(
 					'src'      => $base_url . 'js/externals/hooks.js',
-					'version'  => '2.2.0',
+					'version'  => '2.6.0',
 					'fallback' => true,
 				)
 			),
@@ -700,7 +751,7 @@ private function get_external_assets() {
 				'wp-element',
 				array(
 					'src'      => $base_url . 'js/externals/element.js',
-					'version'  => '2.3.0',
+					'version'  => '2.8.2',
 					'fallback' => true,
 				)
 			),
@@ -708,7 +759,7 @@ private function get_external_assets() {
 				'wp-dom-ready',
 				array(
 					'src'      => $base_url . 'js/externals/domReady.js',
-					'version'  => '2.2.0',
+					'version'  => '2.5.1',
 					'fallback' => true,
 				)
 			),
@@ -716,7 +767,7 @@ private function get_external_assets() {
 				'wp-i18n',
 				array(
 					'src'      => $base_url . 'js/externals/i18n.js',
-					'version'  => '3.3.0',
+					'version'  => '3.6.1',
 					'fallback' => true,
 				)
 			),
@@ -724,7 +775,7 @@ private function get_external_assets() {
 				'wp-url',
 				array(
 					'src'      => $base_url . 'js/externals/url.js',
-					'version'  => '2.3.3',
+					'version'  => '2.8.2',
 					'fallback' => true,
 				)
 			),
@@ -732,13 +783,13 @@ private function get_external_assets() {
 				'wp-api-fetch',
 				array(
 					'src'           => $base_url . 'js/externals/apiFetch.js',
-					'version'       => '2.2.8',
+					'version'       => '3.6.4',
 					'fallback'      => true,
 					'post_register' => function( $handle ) {
 						wp_add_inline_script(
 							$handle,
 							sprintf(
-								'wp.apiFetch.use( wp.apiFetch.createNonceMiddleware( "%s" ) );',
+								'/*googlesitekit*/ wp.apiFetch.use( wp.apiFetch.createNonceMiddleware( "%s" ) );',
 								( wp_installing() && ! is_multisite() ) ? '' : wp_create_nonce( 'wp_rest' )
 							),
 							'after'
@@ -746,7 +797,7 @@ private function get_external_assets() {
 						wp_add_inline_script(
 							$handle,
 							sprintf(
-								'wp.apiFetch.use( wp.apiFetch.createRootURLMiddleware( "%s" ) );',
+								'/*googlesitekit*/ wp.apiFetch.use( wp.apiFetch.createRootURLMiddleware( "%s" ) );',
 								esc_url_raw( get_rest_url() )
 							),
 							'after'
@@ -758,7 +809,7 @@ private function get_external_assets() {
 				'wp-compose',
 				array(
 					'src'      => $base_url . 'js/externals/compose.js',
-					'version'  => '3.2.0',
+					'version'  => '3.7.2',
 					'fallback' => true,
 				)
 			),
diff --git a/package.json b/package.json
index 790aa438ab2..15c01ab4fee 100644
--- a/package.json
+++ b/package.json
@@ -122,9 +122,11 @@
     "@wordpress/dom-ready": "^2.5.1",
     "@wordpress/e2e-test-utils": "^2.1.0",
     "@wordpress/element": "^2.8.2",
+    "@wordpress/escape-html": "^1.5.1",
     "@wordpress/eslint-plugin": "^2.4.0",
     "@wordpress/hooks": "^2.6.0",
     "@wordpress/i18n": "^3.6.1",
+    "@wordpress/is-shallow-equal": "^1.6.1",
     "@wordpress/library-export-default-webpack-plugin": "^1.1.0",
     "@wordpress/scripts": "^3.3.0",
     "@wordpress/url": "^2.8.2",
diff --git a/webpack.config.js b/webpack.config.js
index 2b3b5358d03..2aa42fb982e 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -49,8 +49,10 @@ const externalPackages = [
 	'compose',
 	'dom-ready',
 	'element',
+	'escape-html',
 	'hooks',
 	'i18n',
+	'is-shallow-equal',
 	'url',
 ];