diff --git a/src/Admin/FileImportController.php b/src/Admin/FileImportController.php
index bd93a24..e98be42 100644
--- a/src/Admin/FileImportController.php
+++ b/src/Admin/FileImportController.php
@@ -8,15 +8,18 @@
 namespace WPContentSync\Admin;
 
 use WPContentSync\Logging\LoggerInterface;
+use WPContentSync\Sync\SyncEngine;
 use WPContentSync\Transport\FileTransportInterface;
 
 final class FileImportController {
 	private FileTransportInterface $transport;
 	private LoggerInterface $logger;
+	private SyncEngine $sync_engine;
 
-	public function __construct( FileTransportInterface $transport, LoggerInterface $logger ) {
-		$this->transport = $transport;
-		$this->logger    = $logger;
+	public function __construct( FileTransportInterface $transport, LoggerInterface $logger, SyncEngine $sync_engine ) {
+		$this->transport   = $transport;
+		$this->logger      = $logger;
+		$this->sync_engine = $sync_engine;
 	}
 
 	public function register(): void {
@@ -67,13 +70,23 @@ final class FileImportController {
 			return;
 		}
 
-		$this->logger->info(
-			'Validated imported content package.',
-			array(
-				'schema_version' => $package->schemaVersion(),
-				'manifest'       => $package->manifest(),
-			)
-		);
+		$result = $this->sync_engine->importPackage( $package );
+
+		if ( ! $result->isSuccessful() ) {
+			$this->logger->error(
+				'Imported content package failed.',
+				$result->toArray()
+			);
+
+			$this->redirectToDashboard(
+				array(
+					'wpcs_import_error' => implode( ' ', $result->errors() ),
+				)
+			);
+			return;
+		}
+
+		$this->logger->info( 'Imported content package.', $result->toArray() );
 
 		$this->redirectToDashboard(
 			array(
diff --git a/src/Plugin.php b/src/Plugin.php
index 7681ad3..e5dfa05 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -9,11 +9,18 @@ namespace WPContentSync;
 
 use WPContentSync\Admin\AdminPage;
 use WPContentSync\Admin\FileImportController;
+use WPContentSync\Content\ContentHandlerRegistry;
+use WPContentSync\Content\ContentRecordNormalizer;
+use WPContentSync\Content\MediaContentHandler;
+use WPContentSync\Content\PostContentHandler;
+use WPContentSync\Content\TermContentHandler;
 use WPContentSync\Logging\LoggerInterface;
 use WPContentSync\Logging\OptionLogger;
 use WPContentSync\Package\PackageValidator;
 use WPContentSync\Rest\RestPackageController;
 use WPContentSync\Settings\SettingsRepository;
+use WPContentSync\Sync\SyncEngine;
+use WPContentSync\Sync\SyncStateRepository;
 use WPContentSync\Transport\FileTransportInterface;
 use WPContentSync\Transport\JsonFileTransport;
 use WPContentSync\Transport\RestTransportClient;
@@ -67,6 +74,81 @@ final class Plugin {
 			}
 		);
 
+		$container->factory(
+			ContentRecordNormalizer::class,
+			static function (): ContentRecordNormalizer {
+				return new ContentRecordNormalizer();
+			}
+		);
+
+		$container->factory(
+			PostContentHandler::class,
+			static function () use ( $container ): PostContentHandler {
+				return new PostContentHandler(
+					$container->get( ContentRecordNormalizer::class ),
+					$container->get( UrlTransformer::class ),
+					$container->get( MetadataUrlTransformer::class ),
+					$container->get( LoggerInterface::class )
+				);
+			}
+		);
+
+		$container->factory(
+			TermContentHandler::class,
+			static function () use ( $container ): TermContentHandler {
+				return new TermContentHandler(
+					$container->get( ContentRecordNormalizer::class ),
+					$container->get( UrlTransformer::class ),
+					$container->get( MetadataUrlTransformer::class ),
+					$container->get( LoggerInterface::class )
+				);
+			}
+		);
+
+		$container->factory(
+			MediaContentHandler::class,
+			static function () use ( $container ): MediaContentHandler {
+				return new MediaContentHandler(
+					$container->get( ContentRecordNormalizer::class ),
+					$container->get( UrlTransformer::class ),
+					$container->get( MetadataUrlTransformer::class ),
+					$container->get( LoggerInterface::class )
+				);
+			}
+		);
+
+		$container->factory(
+			ContentHandlerRegistry::class,
+			static function () use ( $container ): ContentHandlerRegistry {
+				return new ContentHandlerRegistry(
+					array(
+						$container->get( PostContentHandler::class ),
+						$container->get( TermContentHandler::class ),
+						$container->get( MediaContentHandler::class ),
+					)
+				);
+			}
+		);
+
+		$container->factory(
+			SyncStateRepository::class,
+			static function (): SyncStateRepository {
+				return new SyncStateRepository();
+			}
+		);
+
+		$container->factory(
+			SyncEngine::class,
+			static function () use ( $container ): SyncEngine {
+				return new SyncEngine(
+					$container->get( ContentHandlerRegistry::class ),
+					$container->get( SyncStateRepository::class ),
+					$container->get( SettingsRepository::class ),
+					$container->get( LoggerInterface::class )
+				);
+			}
+		);
+
 		$container->factory(
 			FileTransportInterface::class,
 			static function () use ( $container ): FileTransportInterface {
@@ -81,7 +163,8 @@ final class Plugin {
 			static function () use ( $container ): FileImportController {
 				return new FileImportController(
 					$container->get( FileTransportInterface::class ),
-					$container->get( LoggerInterface::class )
+					$container->get( LoggerInterface::class ),
+					$container->get( SyncEngine::class )
 				);
 			}
 		);
@@ -97,7 +180,8 @@ final class Plugin {
 			RestPackageController::class,
 			static function () use ( $container ): RestPackageController {
 				return new RestPackageController(
-					$container->get( PackageValidator::class )
+					$container->get( PackageValidator::class ),
+					$container->get( SyncEngine::class )
 				);
 			}
 		);
diff --git a/src/Rest/RestPackageController.php b/src/Rest/RestPackageController.php
index 4e4dcd4..6babc2a 100644
--- a/src/Rest/RestPackageController.php
+++ b/src/Rest/RestPackageController.php
@@ -9,12 +9,15 @@ namespace WPContentSync\Rest;
 
 use WPContentSync\Package\ContentPackage;
 use WPContentSync\Package\PackageValidator;
+use WPContentSync\Sync\SyncEngine;
 
 final class RestPackageController {
 	private PackageValidator $validator;
+	private SyncEngine $sync_engine;
 
-	public function __construct( PackageValidator $validator ) {
-		$this->validator = $validator;
+	public function __construct( PackageValidator $validator, SyncEngine $sync_engine ) {
+		$this->validator   = $validator;
+		$this->sync_engine = $sync_engine;
 	}
 
 	public function register(): void {
@@ -82,11 +85,13 @@ final class RestPackageController {
 		}
 
 		$package = ContentPackage::fromArray( $data['package'] );
+		$import  = $this->sync_engine->importPackage( $package );
 
 		return array(
-			'accepted'       => true,
+			'accepted'       => $import->isSuccessful(),
 			'schema_version' => $package->schemaVersion(),
 			'manifest'       => $package->manifest(),
+			'import'         => $import->toArray(),
 		);
 	}
 
diff --git a/tests/Unit/Admin/FileImportControllerTest.php b/tests/Unit/Admin/FileImportControllerTest.php
index 8e7898c..9b68767 100644
--- a/tests/Unit/Admin/FileImportControllerTest.php
+++ b/tests/Unit/Admin/FileImportControllerTest.php
@@ -4,15 +4,25 @@ namespace WPContentSync\Tests\Unit\Admin;
 
 use PHPUnit\Framework\TestCase;
 use WPContentSync\Admin\FileImportController;
+use WPContentSync\Content\ContentHandlerInterface;
+use WPContentSync\Content\ContentHandlerRegistry;
 use WPContentSync\Logging\LoggerInterface;
 use WPContentSync\Package\PackageChecksum;
 use WPContentSync\Package\PackageValidator;
+use WPContentSync\Settings\SettingsRepository;
+use WPContentSync\Sync\SyncContext;
+use WPContentSync\Sync\SyncEngine;
+use WPContentSync\Sync\SyncResult;
+use WPContentSync\Sync\SyncStateRepository;
 use WPContentSync\Transport\JsonFileTransport;
 
 class FileImportControllerTest extends TestCase {
 	/** @var array<int, string> */
 	private array $temporary_files = array();
 
+	/** @var array<int, array<string, mixed>> */
+	private array $logs = array();
+
 	protected function tearDown(): void {
 		foreach ( $this->temporary_files as $file ) {
 			if ( is_file( $file ) ) {
@@ -21,8 +31,17 @@ class FileImportControllerTest extends TestCase {
 			}
 		}
 
-		unset( $GLOBALS['wpcs_current_user_can'], $GLOBALS['wpcs_nonce_valid'], $GLOBALS['wpcs_redirect_location'] );
-		$_FILES = array();
+		unset(
+			$GLOBALS['wpcs_current_user_can'],
+			$GLOBALS['wpcs_nonce_valid'],
+			$GLOBALS['wpcs_redirect_location'],
+			$GLOBALS['wpcs_test_options'],
+			$GLOBALS['wpcs_test_option_autoloads'],
+			$GLOBALS['wpcs_test_transients'],
+			$GLOBALS['wpcs_test_transient_expiration']
+		);
+		$_FILES     = array();
+		$this->logs = array();
 
 		parent::tearDown();
 	}
@@ -69,7 +88,7 @@ class FileImportControllerTest extends TestCase {
 		$controller->handleImport();
 	}
 
-	public function test_it_imports_valid_uploaded_packages_without_mutating_content(): void {
+	public function test_it_imports_valid_uploaded_packages_with_sync_engine(): void {
 		$file = $this->createTemporaryPackageFile( $this->validJson() );
 
 		$_FILES['wpcs_package_file'] = array(
@@ -80,6 +99,22 @@ class FileImportControllerTest extends TestCase {
 		$this->controller()->handleImport();
 
 		self::assertStringContainsString( 'wpcs_imported=1', $GLOBALS['wpcs_redirect_location'] );
+		self::assertSame( 'Imported content package.', $this->logs[2]['message'] );
+		self::assertSame( 0, $this->logs[2]['context']['created'] );
+	}
+
+	public function test_it_redirects_with_error_when_sync_engine_import_fails(): void {
+		$file = $this->createTemporaryPackageFile( $this->validJson() );
+
+		$_FILES['wpcs_package_file'] = array(
+			'tmp_name' => $file,
+			'error'    => UPLOAD_ERR_OK,
+		);
+
+		$this->controller( SyncResult::failure( array( 'Posts failed.' ) ) )->handleImport();
+
+		self::assertStringContainsString( 'wpcs_import_error=', $GLOBALS['wpcs_redirect_location'] );
+		self::assertStringContainsString( 'Posts+failed.', $GLOBALS['wpcs_redirect_location'] );
 	}
 
 	public function test_it_redirects_with_error_for_invalid_uploaded_packages(): void {
@@ -96,33 +131,84 @@ class FileImportControllerTest extends TestCase {
 		self::assertStringContainsString( 'not+valid+JSON', $GLOBALS['wpcs_redirect_location'] );
 	}
 
-	private function controller(): FileImportController {
+	private function controller( ?SyncResult $result = null ): FileImportController {
+		$logger = $this->logger();
+
 		return new FileImportController(
 			new JsonFileTransport( new PackageValidator() ),
-			new class() implements LoggerInterface {
-				/**
-				 * @param array<string, mixed> $context Context.
-				 */
-				public function error( string $message, array $context = array() ): void {}
-
-				/**
-				 * @param array<string, mixed> $context Context.
-				 */
-				public function warning( string $message, array $context = array() ): void {}
-
-				/**
-				 * @param array<string, mixed> $context Context.
-				 */
-				public function info( string $message, array $context = array() ): void {}
-
-				/**
-				 * @param array<string, mixed> $context Context.
-				 */
-				public function debug( string $message, array $context = array() ): void {}
-			}
+			$logger,
+			$this->syncEngine( $result ?? SyncResult::success() )
 		);
 	}
 
+	private function syncEngine( SyncResult $result ): SyncEngine {
+		return new SyncEngine(
+			new ContentHandlerRegistry( array( $this->handler( $result ) ) ),
+			new SyncStateRepository(),
+			new SettingsRepository(),
+			$this->logger()
+		);
+	}
+
+	private function handler( SyncResult $result ): ContentHandlerInterface {
+		return new class( $result ) implements ContentHandlerInterface {
+			private SyncResult $result;
+
+			public function __construct( SyncResult $result ) {
+				$this->result = $result;
+			}
+
+			public function bucket(): string {
+				return 'posts';
+			}
+
+			public function importRecords( array $records, SyncContext $context ): SyncResult {
+				return $this->result;
+			}
+		};
+	}
+
+	private function logger(): LoggerInterface {
+		return new class( $this->logs ) implements LoggerInterface {
+			/** @var array<int, array<string, mixed>> */
+			private array $logs;
+
+			/**
+			 * @param array<int, array<string, mixed>> $logs Logs.
+			 */
+			public function __construct( array &$logs ) {
+				$this->logs = &$logs;
+			}
+
+			public function error( string $message, array $context = array() ): void {
+				$this->record( 'error', $message, $context );
+			}
+
+			public function warning( string $message, array $context = array() ): void {
+				$this->record( 'warning', $message, $context );
+			}
+
+			public function info( string $message, array $context = array() ): void {
+				$this->record( 'info', $message, $context );
+			}
+
+			public function debug( string $message, array $context = array() ): void {
+				$this->record( 'debug', $message, $context );
+			}
+
+			/**
+			 * @param array<string, mixed> $context Context.
+			 */
+			private function record( string $level, string $message, array $context ): void {
+				$this->logs[] = array(
+					'level'   => $level,
+					'message' => $message,
+					'context' => $context,
+				);
+			}
+		};
+	}
+
 	private function validJson(): string {
 		$records = array(
 			'posts'             => array(),
diff --git a/tests/Unit/PluginTest.php b/tests/Unit/PluginTest.php
index a597111..5427d14 100644
--- a/tests/Unit/PluginTest.php
+++ b/tests/Unit/PluginTest.php
@@ -4,9 +4,16 @@ namespace WPContentSync\Tests\Unit;
 
 use PHPUnit\Framework\TestCase;
 use WPContentSync\Admin\FileImportController;
+use WPContentSync\Content\ContentHandlerRegistry;
+use WPContentSync\Content\ContentRecordNormalizer;
+use WPContentSync\Content\MediaContentHandler;
+use WPContentSync\Content\PostContentHandler;
+use WPContentSync\Content\TermContentHandler;
 use WPContentSync\Container;
 use WPContentSync\Plugin;
 use WPContentSync\Rest\RestPackageController;
+use WPContentSync\Sync\SyncEngine;
+use WPContentSync\Sync\SyncStateRepository;
 use WPContentSync\Transport\FileTransportInterface;
 use WPContentSync\Transport\RestTransportClient;
 use WPContentSync\Url\MetadataUrlTransformer;
@@ -57,6 +64,18 @@ class PluginTest extends TestCase {
 		);
 	}
 
+	public function test_it_registers_sync_engine_and_content_handlers(): void {
+		$container = $this->getPluginContainer( Plugin::create() );
+
+		self::assertInstanceOf( ContentRecordNormalizer::class, $container->get( ContentRecordNormalizer::class ) );
+		self::assertInstanceOf( PostContentHandler::class, $container->get( PostContentHandler::class ) );
+		self::assertInstanceOf( TermContentHandler::class, $container->get( TermContentHandler::class ) );
+		self::assertInstanceOf( MediaContentHandler::class, $container->get( MediaContentHandler::class ) );
+		self::assertInstanceOf( ContentHandlerRegistry::class, $container->get( ContentHandlerRegistry::class ) );
+		self::assertInstanceOf( SyncStateRepository::class, $container->get( SyncStateRepository::class ) );
+		self::assertInstanceOf( SyncEngine::class, $container->get( SyncEngine::class ) );
+	}
+
 	public function test_it_hooks_rest_package_controller_on_register(): void {
 		unset( $GLOBALS['wpcs_test_actions'] );
 
diff --git a/tests/Unit/Rest/RestPackageControllerTest.php b/tests/Unit/Rest/RestPackageControllerTest.php
index d7683c7..fa99da3 100644
--- a/tests/Unit/Rest/RestPackageControllerTest.php
+++ b/tests/Unit/Rest/RestPackageControllerTest.php
@@ -8,9 +8,17 @@
 namespace WPContentSync\Tests\Unit\Rest;
 
 use PHPUnit\Framework\TestCase;
+use WPContentSync\Content\ContentHandlerInterface;
+use WPContentSync\Content\ContentHandlerRegistry;
+use WPContentSync\Logging\LoggerInterface;
 use WPContentSync\Package\PackageChecksum;
 use WPContentSync\Package\PackageValidator;
 use WPContentSync\Rest\RestPackageController;
+use WPContentSync\Settings\SettingsRepository;
+use WPContentSync\Sync\SyncContext;
+use WPContentSync\Sync\SyncEngine;
+use WPContentSync\Sync\SyncResult;
+use WPContentSync\Sync\SyncStateRepository;
 
 class RestPackageControllerTest extends TestCase {
 	protected function setUp(): void {
@@ -20,13 +28,21 @@ class RestPackageControllerTest extends TestCase {
 	}
 
 	protected function tearDown(): void {
-		unset( $GLOBALS['wpcs_rest_routes'], $GLOBALS['wpcs_current_user_can'], $GLOBALS['wpcs_test_actions'] );
+		unset(
+			$GLOBALS['wpcs_rest_routes'],
+			$GLOBALS['wpcs_current_user_can'],
+			$GLOBALS['wpcs_test_actions'],
+			$GLOBALS['wpcs_test_options'],
+			$GLOBALS['wpcs_test_option_autoloads'],
+			$GLOBALS['wpcs_test_transients'],
+			$GLOBALS['wpcs_test_transient_expiration']
+		);
 
 		parent::tearDown();
 	}
 
 	public function test_it_hooks_route_registration_to_rest_api_init(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 		$controller->register();
 
 		self::assertSame(
@@ -36,7 +52,7 @@ class RestPackageControllerTest extends TestCase {
 	}
 
 	public function test_it_registers_status_and_package_routes(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 		$controller->registerRoutes();
 
 		self::assertArrayHasKey( 'wp-content-sync/v1/status', $GLOBALS['wpcs_rest_routes'] );
@@ -45,13 +61,13 @@ class RestPackageControllerTest extends TestCase {
 
 	public function test_it_requires_manage_options_permission(): void {
 		$GLOBALS['wpcs_current_user_can']['manage_options'] = false;
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 
 		self::assertFalse( $controller->canReceivePackage() );
 	}
 
 	public function test_it_returns_status_payload(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 
 		self::assertSame(
 			array(
@@ -64,7 +80,7 @@ class RestPackageControllerTest extends TestCase {
 	}
 
 	public function test_it_accepts_valid_packages(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 
 		self::assertSame(
 			$this->acceptedResponse(),
@@ -77,7 +93,7 @@ class RestPackageControllerTest extends TestCase {
 	}
 
 	public function test_it_accepts_rest_request_like_objects(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 		$request    = new class(
 			array(
 				'package' => $this->validPackage(),
@@ -105,7 +121,7 @@ class RestPackageControllerTest extends TestCase {
 	}
 
 	public function test_it_rejects_invalid_package_shapes(): void {
-		$controller = new RestPackageController( new PackageValidator() );
+		$controller = $this->controller();
 
 		self::assertSame(
 			array(
@@ -116,6 +132,36 @@ class RestPackageControllerTest extends TestCase {
 		);
 	}
 
+	public function test_it_returns_rejected_response_when_sync_import_fails(): void {
+		$controller = $this->controller( SyncResult::failure( array( 'Posts failed.' ) ) );
+
+		self::assertSame(
+			array(
+				'accepted'       => false,
+				'schema_version' => '1.0',
+				'manifest'       => array(
+					'posts'             => 0,
+					'terms'             => 0,
+					'media'             => 0,
+					'custom_post_types' => 0,
+				),
+				'import'         => array(
+					'successful' => false,
+					'created'    => 0,
+					'updated'    => 0,
+					'skipped'    => 0,
+					'conflicts'  => 0,
+					'errors'     => array( 'Posts failed.' ),
+				),
+			),
+			$controller->receivePackage(
+				array(
+					'package' => $this->validPackage(),
+				)
+			)
+		);
+	}
+
 	/**
 	 * @return array<string, mixed>
 	 */
@@ -129,9 +175,63 @@ class RestPackageControllerTest extends TestCase {
 				'media'             => 0,
 				'custom_post_types' => 0,
 			),
+			'import'         => array(
+				'successful' => true,
+				'created'    => 0,
+				'updated'    => 0,
+				'skipped'    => 0,
+				'conflicts'  => 0,
+				'errors'     => array(),
+			),
 		);
 	}
 
+	private function controller( ?SyncResult $result = null ): RestPackageController {
+		return new RestPackageController(
+			new PackageValidator(),
+			$this->syncEngine( $result ?? SyncResult::success() )
+		);
+	}
+
+	private function syncEngine( SyncResult $result ): SyncEngine {
+		return new SyncEngine(
+			new ContentHandlerRegistry( array( $this->handler( $result ) ) ),
+			new SyncStateRepository(),
+			new SettingsRepository(),
+			$this->logger()
+		);
+	}
+
+	private function handler( SyncResult $result ): ContentHandlerInterface {
+		return new class( $result ) implements ContentHandlerInterface {
+			private SyncResult $result;
+
+			public function __construct( SyncResult $result ) {
+				$this->result = $result;
+			}
+
+			public function bucket(): string {
+				return 'posts';
+			}
+
+			public function importRecords( array $records, SyncContext $context ): SyncResult {
+				return $this->result;
+			}
+		};
+	}
+
+	private function logger(): LoggerInterface {
+		return new class() implements LoggerInterface {
+			public function error( string $message, array $context = array() ): void {}
+
+			public function warning( string $message, array $context = array() ): void {}
+
+			public function info( string $message, array $context = array() ): void {}
+
+			public function debug( string $message, array $context = array() ): void {}
+		};
+	}
+
 	/**
 	 * @return array<string, mixed>
 	 */