diff --git a/includes/Checker/Checks/Performance/Non_Blocking_Scripts_Check.php b/includes/Checker/Checks/Performance/Non_Blocking_Scripts_Check.php
new file mode 100644
index 000000000..d7b46a0f2
--- /dev/null
+++ b/includes/Checker/Checks/Performance/Non_Blocking_Scripts_Check.php
@@ -0,0 +1,243 @@
+<?php
+/**
+ * Class Non_Blocking_Scripts_Check.
+ *
+ * @package plugin-check
+ */
+
+namespace WordPress\Plugin_Check\Checker\Checks\Performance;
+
+use Exception;
+use WordPress\Plugin_Check\Checker\Check_Categories;
+use WordPress\Plugin_Check\Checker\Check_Result;
+use WordPress\Plugin_Check\Checker\Checks\Abstract_Runtime_Check;
+use WordPress\Plugin_Check\Checker\Preparations\Demo_Posts_Creation_Preparation;
+use WordPress\Plugin_Check\Checker\With_Shared_Preparations;
+use WordPress\Plugin_Check\Traits\Amend_Check_Result;
+use WordPress\Plugin_Check\Traits\Stable_Check;
+use WordPress\Plugin_Check\Traits\URL_Aware;
+
+/**
+ * Check for non-blocking scripts.
+ *
+ * @since 1.1.0
+ */
+class Non_Blocking_Scripts_Check extends Abstract_Runtime_Check implements With_Shared_Preparations {
+
+	use Amend_Check_Result;
+	use Stable_Check;
+	use URL_Aware;
+
+	/**
+	 * List of viewable post types.
+	 *
+	 * @since 1.1.0
+	 * @var array
+	 */
+	private $viewable_post_types;
+
+	/**
+	 * Gets the categories for the check.
+	 *
+	 * Every check must have at least one category.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @return array The categories for the check.
+	 */
+	public function get_categories() {
+		return array( Check_Categories::CATEGORY_PERFORMANCE );
+	}
+
+	/**
+	 * Runs this preparation step for the environment and returns a cleanup function.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @return callable Cleanup function to revert any changes made here.
+	 *
+	 * @throws Exception Thrown when preparation fails.
+	 */
+	public function prepare() {
+		$orig_scripts = isset( $GLOBALS['wp_scripts'] ) ? $GLOBALS['wp_scripts'] : null;
+
+		// Backup the original values for the global state.
+		$this->backup_globals();
+
+		return function () use ( $orig_scripts ) {
+			if ( is_null( $orig_scripts ) ) {
+				unset( $GLOBALS['wp_scripts'] );
+			} else {
+				$GLOBALS['wp_scripts'] = $orig_scripts;
+			}
+
+			$this->restore_globals();
+		};
+	}
+
+	/**
+	 * Returns an array of shared preparations for the check.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @return array Returns a map of $class_name => $constructor_args pairs. If the class does not
+	 *               need any constructor arguments, it would just be an empty array.
+	 */
+	public function get_shared_preparations() {
+		$demo_posts = array_map(
+			static function ( $post_type ) {
+				return array(
+					'post_title'   => "Demo {$post_type} post",
+					'post_content' => 'Test content',
+					'post_type'    => $post_type,
+					'post_status'  => 'publish',
+				);
+			},
+			$this->get_viewable_post_types()
+		);
+
+		return array(
+			Demo_Posts_Creation_Preparation::class => array( $demo_posts ),
+		);
+	}
+
+	/**
+	 * Runs the check on the plugin and amends results.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @param Check_Result $result The check results to amend and the plugin context.
+	 */
+	public function run( Check_Result $result ) {
+		$this->run_for_urls(
+			$this->get_urls(),
+			function ( $url ) use ( $result ) {
+				$this->check_url( $result, $url );
+			}
+		);
+	}
+
+	/**
+	 * Gets the list of URLs to run this check for.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @return array List of URL strings (either full URLs or paths).
+	 *
+	 * @throws Exception Thrown when a post type URL cannot be retrieved.
+	 */
+	protected function get_urls() {
+		$urls = array( home_url() );
+
+		foreach ( $this->get_viewable_post_types() as $post_type ) {
+			$posts = get_posts(
+				array(
+					'posts_per_page' => 1,
+					'post_type'      => $post_type,
+					'post_status'    => array( 'publish', 'inherit' ),
+				)
+			);
+
+			if ( ! isset( $posts[0] ) ) {
+				throw new Exception(
+					sprintf(
+						/* translators: %s: The Post Type name. */
+						__( 'Unable to retrieve post URL for post type: %s', 'plugin-check' ),
+						$post_type
+					)
+				);
+			}
+
+			$urls[] = get_permalink( $posts[0] );
+		}
+
+		return $urls;
+	}
+
+	/**
+	 * Amends the given result by running the check for the given URL.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @param Check_Result $result The check result to amend, including the plugin context to check.
+	 * @param string       $url    URL to run the check for.
+	 *
+	 * @throws Exception Thrown when the check fails with a critical error (unrelated to any errors detected as part of
+	 *                   the check).
+	 *
+	 * @SuppressWarnings(PHPMD.NPathComplexity)
+	 */
+	protected function check_url( Check_Result $result, $url ) {
+		// Reset the WP_Scripts instance.
+		unset( $GLOBALS['wp_scripts'] );
+
+		// Run the 'wp_enqueue_script' action, wrapped in an output buffer in case of any callbacks printing scripts
+		// directly. This is discouraged, but some plugins or themes are still doing it.
+		ob_start();
+		wp_enqueue_scripts();
+		wp_scripts()->do_head_items();
+		wp_scripts()->do_footer_items();
+		ob_end_clean();
+
+		foreach ( wp_scripts()->done as $handle ) {
+			$script = wp_scripts()->registered[ $handle ];
+
+			// TODO: Somehow detect inline scripts added by the plugin that don't have a `src`.
+
+			if ( ! $script->src || strpos( $script->src, $result->plugin()->url() ) !== 0 ) {
+				continue;
+			}
+
+			if ( ! empty( $script->extra['strategy'] ) ) {
+				continue;
+			}
+
+			$script_path = str_replace( $result->plugin()->url(), $result->plugin()->path(), $script->src );
+
+			if ( ! in_array( $handle, wp_scripts()->in_footer, true ) ) {
+				$this->add_result_warning_for_file(
+					$result,
+					sprintf(
+						/* translators: 1: tested URL. 2: the script handle. 3: 'defer'. 4: 'async' */
+						__( 'This script on %1$s (with handle %2$s) is potentially blocking. Consider a %3$s or %4$s script strategy or moving it to the footer.', 'plugin-check' ),
+						$url,
+						$handle,
+						'defer',
+						'async'
+					),
+					'NonBlockingScripts.BlockingHeadScript',
+					$script_path
+				);
+			} else {
+				$this->add_result_warning_for_file(
+					$result,
+					sprintf(
+						/* translators: 1: tested URL. 2: the script handle. 3: 'defer'. 4: 'async' */
+						__( 'This script on %1$s (with handle %2$s) is loaded in the footer. Consider a %3$s or %4$s script loading strategy instead.', 'plugin-check' ),
+						$url,
+						$handle,
+						'defer',
+						'async'
+					),
+					'NonBlockingScripts.NoStrategy',
+					$script_path
+				);
+			}
+		}
+	}
+
+	/**
+	 * Returns an array of viewable post types.
+	 *
+	 * @since 1.1.0
+	 *
+	 * @return array Array of viewable post type slugs.
+	 */
+	private function get_viewable_post_types() {
+		if ( ! is_array( $this->viewable_post_types ) ) {
+			$this->viewable_post_types = array_filter( get_post_types(), 'is_post_type_viewable' );
+		}
+
+		return $this->viewable_post_types;
+	}
+}
diff --git a/includes/Checker/Default_Check_Repository.php b/includes/Checker/Default_Check_Repository.php
index 4d68f1793..171fb117d 100644
--- a/includes/Checker/Default_Check_Repository.php
+++ b/includes/Checker/Default_Check_Repository.php
@@ -58,6 +58,7 @@ private function register_default_checks() {
 				'localhost'                  => new Checks\Plugin_Repo\Localhost_Check(),
 				'no_unfiltered_uploads'      => new Checks\Plugin_Repo\No_Unfiltered_Uploads_Check(),
 				'trademarks'                 => new Checks\Plugin_Repo\Trademarks_Check(),
+				'non_blocking_scripts'       => new Checks\Performance\Non_Blocking_Scripts_Check(),
 			)
 		);
 
diff --git a/tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/load.php b/tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/load.php
new file mode 100644
index 000000000..e46b0cef1
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/load.php
@@ -0,0 +1,50 @@
+<?php
+/**
+ * File contains errors for the non blocking scripts check.
+ */
+
+add_action(
+	'wp_enqueue_scripts',
+	function() {
+		wp_enqueue_script(
+			'plugin_check_test_script_header',
+			plugin_dir_url( __FILE__ ) . 'header.js',
+			array(),
+			false,
+			array(
+				'in_footer' => false,
+			)
+		);
+
+		wp_enqueue_script(
+			'plugin_check_test_script_footer',
+			plugin_dir_url( __FILE__ ) . 'footer.js',
+			array(),
+			false,
+			array(
+				'in_footer' => true,
+			)
+		);
+
+		wp_enqueue_script(
+			'plugin_check_test_script_defer',
+			plugin_dir_url( __FILE__ ) . 'defer.js',
+			array(),
+			false,
+			array(
+				'strategy' => 'defer'
+			)
+		);
+
+		wp_enqueue_script(
+			'plugin_check_test_script_async',
+			plugin_dir_url( __FILE__ ) . 'async.js',
+			array(),
+			false,
+			array(
+				'strategy' => 'async'
+			)
+		);
+	}
+);
+
diff --git a/tests/phpunit/tests/Checker/Checks/Non_Blocking_Scripts_Check_Tests.php b/tests/phpunit/tests/Checker/Checks/Non_Blocking_Scripts_Check_Tests.php
new file mode 100644
index 000000000..67362028f
--- /dev/null
+++ b/tests/phpunit/tests/Checker/Checks/Non_Blocking_Scripts_Check_Tests.php
@@ -0,0 +1,89 @@
+<?php
+/**
+ * Tests for the Non_Blocking_Scripts_Check class.
+ *
+ * @package plugin-check
+ */
+
+use WordPress\Plugin_Check\Checker\Checks\Performance\Non_Blocking_Scripts_Check;
+use WordPress\Plugin_Check\Checker\Preparation;
+use WordPress\Plugin_Check\Test_Utils\TestCase\Runtime_Check_UnitTestCase;
+
+class Non_Blocking_Scripts_Check_Tests extends Runtime_Check_UnitTestCase {
+
+	public function test_get_shared_preparations() {
+		$check        = new Non_Blocking_Scripts_Check();
+		$preparations = $check->get_shared_preparations();
+
+		$this->assertIsArray( $preparations );
+
+		foreach ( $preparations as $class => $args ) {
+			$instance = new $class( ...$args );
+			$this->assertInstanceOf( Preparation::class, $instance );
+		}
+	}
+
+	public function test_prepare() {
+		// Create variables in global state.
+		$_GET['test_prepare']    = true;
+		$_POST['test_prepare']   = true;
+		$_SERVER['test_prepare'] = true;
+
+		$current_screen            = $GLOBALS['current_screen'];
+		$GLOBALS['current_screen'] = 'test_prepare';
+
+		$check   = new Non_Blocking_Scripts_Check();
+		$cleanup = $check->prepare();
+
+		// Modify the variables in the global state.
+		$_GET['test_prepare']      = false;
+		$_POST['test_prepare']     = false;
+		$_SERVER['test_prepare']   = false;
+		$GLOBALS['current_screen'] = 'altered';
+
+		$cleanup();
+
+		$test_get     = $_GET['test_prepare'];
+		$test_post    = $_POST['test_prepare'];
+		$test_server  = $_SERVER['test_prepare'];
+		$test_globals = $GLOBALS['current_screen'];
+
+		// Restore the global state.
+		unset( $_GET['test_prepare'] );
+		unset( $_POST['test_prepare'] );
+		unset( $_SERVER['test_prepare'] );
+		$GLOBALS['current_screen'] = $current_screen;
+
+		$this->assertTrue( $test_get );
+		$this->assertTrue( $test_post );
+		$this->assertTrue( $test_server );
+		$this->assertSame( 'test_prepare', $test_globals );
+	}
+
+	public function test_run_with_warnings() {
+		require UNIT_TESTS_PLUGIN_DIR . 'test-plugin-non-blocking-scripts-check/load.php';
+
+		$check   = new Non_Blocking_Scripts_Check();
+		$context = $this->get_context( WP_PLUGIN_CHECK_MAIN_FILE );
+		$results = $this->run_check( $check, $context );
+
+		$errors   = $results->get_errors();
+		$warnings = $results->get_warnings();
+
+		$this->assertEmpty( $errors );
+		$this->assertNotEmpty( $warnings );
+
+		$header_script = 'tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/header.js';
+		$footer_script = 'tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/footer.js';
+		$async_script  = 'tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/async.js';
+		$defer_script  = 'tests/phpunit/testdata/plugins/test-plugin-non-blocking-scripts-check/defer.js';
+
+		$this->assertArrayNotHasKey( $async_script, $warnings, 'An async script should not cause any warnings' );
+		$this->assertArrayNotHasKey( $defer_script, $warnings, 'A deferred script should not cause any warnings' );
+		$this->assertArrayHasKey( $header_script, $warnings, 'A header script should cause a warning' );
+		$this->assertArrayHasKey( $footer_script, $warnings, 'A footer script should cause a warning' );
+
+		$this->assertSame( 'NonBlockingScripts.BlockingHeadScript', $warnings[ $header_script ][0][0][0]['code'] );
+		$this->assertSame( 'NonBlockingScripts.NoStrategy', $warnings[ $footer_script ][0][0][0]['code'] );
+	}
+}