diff --git a/src/Type/AbstractType.php b/src/Type/AbstractType.php
index 5f3620d..e8e5102 100644
--- a/src/Type/AbstractType.php
+++ b/src/Type/AbstractType.php
@@ -7,8 +7,10 @@
 use Palmtree\ArgParser\ArgParser;
 use Palmtree\Form\Constraint\ConstraintInterface;
 use Palmtree\Form\Constraint\NotBlank;
+use Palmtree\Form\Exception\InvalidTypeException;
 use Palmtree\Form\Exception\OutOfBoundsException;
 use Palmtree\Form\Form;
+use Palmtree\Form\TypeLocator;
 use Palmtree\Html\Element;
 use Palmtree\NameConverter\SnakeCaseToCamelCaseNameConverter;
 use Palmtree\NameConverter\SnakeCaseToHumanNameConverter;
@@ -45,6 +47,8 @@ abstract class AbstractType implements TypeInterface
     protected $constraints = [];
     /** @var SnakeCaseToHumanNameConverter */
     protected $nameConverter;
+    /** @var TypeLocator */
+    protected $typeLocator;
     /** @var bool */
     protected $mapped = true;
     /** @var array */
@@ -56,6 +60,7 @@ abstract class AbstractType implements TypeInterface
     public function __construct(array $args = [])
     {
         $this->nameConverter = new SnakeCaseToHumanNameConverter();
+        $this->typeLocator = new TypeLocator();
 
         $this->args = $this->parseArgs($args);
 
@@ -384,8 +389,13 @@ public function addChild(TypeInterface $child): TypeInterface
 
     public function add(string $name, string $class, array $options = []): TypeInterface
     {
+        if (!$class = $this->typeLocator->getTypeClass($class)) {
+            throw new InvalidTypeException('Type could not be found');
+        }
+
         /** @var TypeInterface $type */
         $type = new $class($options);
+
         $type->setName($name);
 
         if ($type->getLabel() === null) {
diff --git a/src/Type/CollectionType.php b/src/Type/CollectionType.php
index dec91f6..2ef5cd2 100644
--- a/src/Type/CollectionType.php
+++ b/src/Type/CollectionType.php
@@ -4,6 +4,7 @@
 
 namespace Palmtree\Form\Type;
 
+use Palmtree\Form\Exception\InvalidTypeException;
 use Palmtree\Html\Element;
 
 class CollectionType extends AbstractType
@@ -61,11 +62,15 @@ public function addChild(TypeInterface $child): TypeInterface
     }
 
     /**
-     * @psalm-param class-string<TypeInterface> $entryType
+     * @psalm-param class-string<TypeInterface>|string $entryType
      */
     public function setEntryType(string $entryType): void
     {
-        $this->entryType = $entryType;
+        if (!$class = $this->typeLocator->getTypeClass($entryType)) {
+            throw new InvalidTypeException('Type could not be found');
+        }
+
+        $this->entryType = $class;
     }
 
     /**
@@ -141,6 +146,14 @@ private function buildEntry(int $position = 0, $data = null): TypeInterface
 
         if (\func_num_args() > 0) {
             $entry->setData($data);
+
+            if (\is_array($data)) {
+                foreach ($entry->all() as $child) {
+                    if (isset($data[$child->getName()])) {
+                        $child->setData($data[$child->getName()]);
+                    }
+                }
+            }
         }
 
         return $entry;
diff --git a/src/TypeLocator.php b/src/TypeLocator.php
index 4955614..087d3f2 100644
--- a/src/TypeLocator.php
+++ b/src/TypeLocator.php
@@ -9,7 +9,7 @@
 
 class TypeLocator
 {
-    /** @var array<string, string> Map of types where key is the shorthand name e.g 'text' and value is the FCQN. */
+    /** @var array<string, class-string<TypeInterface>> Map of types where key is the shorthand name e.g 'text' and value is the FCQN. */
     private static $types = [];
 
     private const TYPE_KEYS = [
@@ -21,11 +21,18 @@ public function __construct()
     {
         if (empty(self::$types)) {
             foreach (glob(__DIR__ . '/Type/*Type.php', \GLOB_NOSORT) ?: [] as $file) {
-                self::$types[strtolower(basename($file, 'Type.php'))] = __NAMESPACE__ . '\\Type\\' . basename($file, '.php');
+                /** @var class-string<TypeInterface> $class */
+                $class = __NAMESPACE__ . '\\Type\\' . basename($file, '.php');
+                self::$types[strtolower(basename($file, 'Type.php'))] = $class;
             }
         }
     }
 
+    /**
+     * @param string|class-string<TypeInterface> $type
+     *
+     * @return class-string<TypeInterface>|null
+     */
     public function getTypeClass(string $type): ?string
     {
         if (isset(self::$types[$type])) {
@@ -33,6 +40,7 @@ public function getTypeClass(string $type): ?string
         }
 
         if (class_exists($type)) {
+            /** @var class-string<TypeInterface> */
             return $type;
         }
 
diff --git a/tests/DataBindingTest.php b/tests/DataBindingTest.php
index 8daf536..3763882 100644
--- a/tests/DataBindingTest.php
+++ b/tests/DataBindingTest.php
@@ -8,6 +8,8 @@
 use Palmtree\Form\Form;
 use Palmtree\Form\FormBuilder;
 use Palmtree\Form\Test\Fixtures\Person;
+use Palmtree\Form\Test\Fixtures\PersonType;
+use Palmtree\Form\Type\CollectionType;
 use PHPUnit\Framework\TestCase;
 
 class DataBindingTest extends TestCase
@@ -168,6 +170,83 @@ public function testArrayAccessDataMapperThrowsOutOfBoundsException(): void
         ]);
     }
 
+    public function testCollectionOneWayDataBinding(): void
+    {
+        $data = [
+            'people' => [
+                [
+                    'name' => 'John Smith',
+                    'emailAddress' => 'john.smith@example.org',
+                    'age' => 42,
+                    'favouriteConsole' => 'PlayStation',
+                    'interests' => ['football', 'gaming'],
+                    'signup' => false,
+                    'pets' => [],
+                ],
+            ],
+        ];
+
+        $builder = new FormBuilder('test', $data);
+
+        $builder->add('people', CollectionType::class, [
+            'entry_type' => PersonType::class,
+        ]);
+
+        $builder->add('send_message', 'submit');
+
+        $form = $builder->getForm();
+        $form->render();
+
+        $formPeople = $form->get('people')->getData();
+
+        self::assertSame($data['people'], $formPeople);
+    }
+
+    public function testCollectionTwoWayDataBinding(): void
+    {
+        $data = new \ArrayObject([
+            'people' => [
+                [
+                    'name' => 'John Smith',
+                    'emailAddress' => 'john.smith@example.org',
+                    'age' => 42,
+                    'favouriteConsole' => 'PlayStation',
+                    'interests' => ['football', 'gaming'],
+                    'signup' => false,
+                    'pets' => [],
+                ],
+            ],
+        ]);
+
+        $builder = new FormBuilder('test', $data);
+
+        $builder->add('people', CollectionType::class, [
+            'entry_type' => PersonType::class,
+        ]);
+
+        $builder->add('send_message', 'submit');
+
+        $form = $builder->getForm();
+
+        $form->submit([
+            'people' => [
+                [
+                    'name' => 'Bob Smith',
+                    'emailAddress' => 'bob.smith@example.org',
+                    'age' => 45,
+                    'favouriteConsole' => 'Xbox',
+                    'interests' => ['guitar'],
+                ],
+            ],
+        ]);
+
+        self::assertSame($data['people'][0]['name'], 'Bob Smith');
+        self::assertSame($data['people'][0]['emailAddress'], 'bob.smith@example.org');
+        self::assertSame($data['people'][0]['age'], 45);
+        self::assertSame($data['people'][0]['favouriteConsole'], 'Xbox');
+        self::assertSame($data['people'][0]['interests'], ['guitar']);
+    }
+
     /**
      * @param Person|array|\ArrayAccess|\stdClass $person
      */
@@ -201,7 +280,8 @@ private function buildForm($person): Form
             ])
             ->add('pets', 'collection', [
                 'entry_type' => 'text',
-            ]);
+            ])
+        ;
 
         return $builder->getForm();
     }