diff --git a/public/class-reuna-mailchimp-public.php b/public/class-reuna-mailchimp-public.php
index 69e9fe9..614b4dd 100644
--- a/public/class-reuna-mailchimp-public.php
+++ b/public/class-reuna-mailchimp-public.php
@@ -42,6 +42,24 @@ class Reuna_Mailchimp_Public {
 	 */
 	private $version;
 
+	/**
+	 * The MailChimp API key
+	 *
+	 * @since    1.0.0
+	 * @access   private
+	 * @var      string    $api_key    The MailChimp API key
+	 */
+	private $api_key;
+
+	/**
+	 * The MailChimp list ID
+	 *
+	 * @since    1.0.0
+	 * @access   private
+	 * @var      string    $list_id    The MailChimp list ID
+	 */
+	private $list_id;
+
 	/**
 	 * Initialize the class and set its properties.
 	 *
@@ -77,14 +95,9 @@ class Reuna_Mailchimp_Public {
 	 */
 	public function register_rest_api_routes() 
 	{
-		register_rest_route($this->plugin_name . '/v1', '/subscribe/(?P<list_id>\w+)', [
+		register_rest_route($this->plugin_name . '/v1', '/subscribe', [
 			'methods' => 'POST',
-			'callback' => [$this, 'subscribe_user_to_list'],
-			'args' => [
-				'list_id' => [
-					'required' => true,
-				],
-			],
+			'callback' => [$this, 'handle_rest_api_request'],
 			'permission_callback' => function () {
 				return current_user_can('read');
 			}
@@ -92,31 +105,108 @@ class Reuna_Mailchimp_Public {
 	}
 
 	/**
-	 * Add a subscriber
+	 * Handle the REST API Request
+	 *
+	 * @since    1.0.0
+	 */
+	public function handle_rest_api_request(WP_REST_Request $request) 
+	{
+		$this->setup_environment();
+		$user = wp_get_current_user();
+
+		if (! $this->subscriber_exists($user)) {
+			$this->create_subscriber($user);
+		}
+
+		$tags = $request->get_param('tags');
+		if (! is_array($tags)) {
+			return;
+		}
+
+		$this->add_subscriber_tags($user, $tags);
+	}
+
+	/**
+	 * Setup class properties from environment variables
 	 *
 	 * @since    1.0.0
 	 */
-	public function subscribe_user_to_list(WP_REST_Request $request) 
+	protected function setup_environment()
 	{
 		if (! function_exists('env')) {
 			return new WP_Error('missing_env');
 		}
 
-		$api_key = env('MAILCHIMP_API_KEY');
-		if (! $api_key) {
+		$this->api_key = env('MAILCHIMP_API_KEY');
+		if (! $this->api_key) {
 			return new WP_Error('missing_mailchimp_api_key');
 		}
 
-		$user = wp_get_current_user();
+		$this->list_id = env('MAILCHIMP_LIST_ID');
+		if (! $this->list_id) {
+			return new WP_Error('missing_mailchimp_list_id');
+		}
+	}
+
+	/**
+	 * Check if a user is already subscribed to a list
+	 *
+	 * @since    1.0.0
+	 */
+	protected function subscriber_exists($user)
+	{
+		$mailchimp =  new Mailchimp($this->api_key);
+		$subscriber_hash = MailChimp::subscriberHash($user->user_email);
+
+		$mailchimp->get('lists/' . $this->list_id . '/members/' . $subscriber_hash);
+
+		return $mailchimp->success();
+	}
+
+	/**
+	 * Add tags to an existing subscriber
+	 *
+	 * @since    1.0.0
+	 */
+	protected function add_subscriber_tags(WP_User $user, array $tags)
+	{
+		$mailchimp =  new Mailchimp($this->api_key);
+		$subscriber_hash = MailChimp::subscriberHash($user->user_email);
+
+		$existing_tags = $mailchimp->get('lists/' . $this->list_id . '/members/' . $subscriber_hash . '/tags');
+		$existing_tags = array_column($existing_tags, 'name');
+
+		$new_tags = array_values(array_unique(array_merge($existing_tags, $tags)));
+		$new_tags = array_map(function($tag) {
+			return [
+				'name' => $tag,
+				'status' => 'active',
+			];
+		}, $new_tags);
+
+		return $mailchimp->post('lists/' . $this->list_id . '/members/' . $subscriber_hash . '/tags', [
+			'tags' => $new_tags,
+		]);
+	}
 
-		$mailchimp = new MailChimp($api_key);
-		$mailchimp->post(
-			'lists/' . $request->get_param('list_id') . '/members',
-			[
-				'email_address' => $user->user_email,
-			]
-		);
+	/**
+	 * Subscribe user to list
+	 *
+	 * @since    1.0.0
+	 */
+	protected function create_subscriber(WP_User $user)
+	{
+		$mailchimp = new Mailchimp($this->api_key);
+
+		$options = [
+			'email_address' => $user->user_email,
+			'status' => 'subscribed',
+			'merge_fields' => [
+				'FNAME' => $user->first_name,
+				'LNAME' => $user->last_name,
+			],
+		];
 
-		return true;
+		return $mailchimp->post('lists/' . $this->list_id . '/members', $options);
 	}
 }
diff --git a/public/js/reuna-mailchimp-public.js b/public/js/reuna-mailchimp-public.js
index 41aeb98..33415d8 100644
--- a/public/js/reuna-mailchimp-public.js
+++ b/public/js/reuna-mailchimp-public.js
@@ -3,12 +3,14 @@
 
 	$(window).on('reuna-mailchimp-subscribe', function(event) {
 		$.ajax({
-			url: wpApiSettings.root + 'reuna-mailchimp/v1/subscribe/' + event.detail.list_id,
+			url: wpApiSettings.root + 'reuna-mailchimp/v1/subscribe/',
 			method: 'POST',
 			beforeSend: function (xhr) {
 				xhr.setRequestHeader('X-WP-Nonce', wpApiSettings.nonce);
 			},
-			data: {}
+			data: {
+				tags: event.detail.tags,
+			},
 		}).done(function(response) {});
 	});