diff --git a/.distignore b/.distignore
index 7dacb1d..f242837 100644
--- a/.distignore
+++ b/.distignore
@@ -4,7 +4,6 @@
 /.wordpress-org
 /node_modules
 /tests
-/vendor
 
 # Files to ignore
 /.*
diff --git a/.gitattributes b/.gitattributes
index 541a824..0324b53 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -2,7 +2,6 @@
 /.wordpress-org export-ignore
 /node_modules export-ignore
 /tests export-ignore
-/vendor export-ignore
 
 /.* export-ignore
 /CHANGELOG.md export-ignore
diff --git a/.github/workflows/build-release-zip.yml b/.github/workflows/build-release-zip.yml
index d389693..597a51b 100644
--- a/.github/workflows/build-release-zip.yml
+++ b/.github/workflows/build-release-zip.yml
@@ -35,6 +35,11 @@ jobs:
         if: steps.cache-node-modules.outputs.cache-hit != 'true'
         run: npm ci --no-optional
 
+      - name: Install Composer dependencies and dump autoload
+        run: |
+          composer install --no-dev --optimize-autoloader
+          composer dump-autoload
+
       - name: Build plugin
         run: |
           npm run build
@@ -47,4 +52,4 @@ jobs:
       - name: Generate ZIP file
         uses: 10up/action-wordpress-plugin-build-zip@stable
         env:
-          SLUG: mailchimp
+          SLUG: mailchimp
\ No newline at end of file
diff --git a/.github/workflows/wordpress-plugin-asset-update.yml b/.github/workflows/wordpress-plugin-asset-update.yml
index 12a9bfb..499dc33 100644
--- a/.github/workflows/wordpress-plugin-asset-update.yml
+++ b/.github/workflows/wordpress-plugin-asset-update.yml
@@ -20,6 +20,11 @@ jobs:
           node-version-file: .nvmrc
           cache: npm
 
+      - name: Install Composer dependencies and dump autoload
+        run: |
+          composer install --no-dev --optimize-autoloader
+          composer dump-autoload
+
       - name: Build
         run: |
           npm ci --no-optional
diff --git a/.github/workflows/wordpress-plugin-deploy.yml b/.github/workflows/wordpress-plugin-deploy.yml
index f2a9dff..3e8db49 100644
--- a/.github/workflows/wordpress-plugin-deploy.yml
+++ b/.github/workflows/wordpress-plugin-deploy.yml
@@ -19,6 +19,11 @@ jobs:
         node-version-file: '.nvmrc'
         cache: 'npm'
 
+    - name: Install Composer dependencies and dump autoload
+      run: |
+        composer install --no-dev --optimize-autoloader
+        composer dump-autoload
+
     - name: Build
       run: |
         npm ci --no-optional
@@ -47,4 +52,4 @@ jobs:
         upload_url: ${{ github.event.release.upload_url }}
         asset_path: ${{ steps.deploy.outputs.zip-path }}
         asset_name: mailchimp.zip
-        asset_content_type: application/zip
+        asset_content_type: application/zip
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 2f2b77a..9965490 100644
--- a/composer.json
+++ b/composer.json
@@ -18,6 +18,14 @@
     "10up/phpcs-composer": "^3.0",
 	  "sirbrillig/phpcs-changed": "^2.11"
   },
+  "autoload": {
+    "psr-4": {
+      "Mailchimp\\WordPress\\": "src/"
+    },
+    "classmap": [
+      "includes"
+    ]
+  },
   "config": {
     "allow-plugins": {
       "dealerdirect/phpcodesniffer-composer-installer": true
@@ -26,4 +34,4 @@
   "scripts": {
     "lint": "phpcs --standard=./phpcs.xml -p -s ."
   }
-}
+}
\ No newline at end of file
diff --git a/mailchimp.php b/mailchimp.php
index f9870e5..45a2d1f 100644
--- a/mailchimp.php
+++ b/mailchimp.php
@@ -34,6 +34,36 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+// Check if the autoload file exists
+if ( is_readable( __DIR__ . '/vendor/autoload.php' ) ) {
+	require_once __DIR__ . '/vendor/autoload.php';
+} else {
+	add_action(
+		'admin_notices',
+		function () {
+			?>
+			<div class="notice notice-error">
+				<p>
+					<?php
+					echo wp_kses_post(
+						sprintf(
+							/* translators: 1: Command to run, e.g., <code>composer install</code>, 2: Support URL, e.g., https://wordpress.org/support/plugin/mailchimp/. */
+							__( 'The composer autoload file is not found or not readable. Please contact <a href="%2$s" target="_blank">support</a> if you\'re a user. Please run %1$s if you\'re a developer in a development environment.', 'mailchimp' ),
+							'<code>composer install</code>',
+							'https://wordpress.org/support/plugin/mailchimp/'
+						)
+					);
+					?>
+				</p>
+			</div>
+			<?php
+		}
+	);
+
+	// Exit early.
+	return;
+}
+
 // Version constant for easy CSS refreshes
 define( 'MCSF_VER', '1.6.2' );