diff --git a/core/lib/Drupal/Core/TypedData/Primitive.php b/core/lib/Drupal/Core/TypedData/Primitive.php
index a2c8125..02fc6b4 100644
--- a/core/lib/Drupal/Core/TypedData/Primitive.php
+++ b/core/lib/Drupal/Core/TypedData/Primitive.php
@@ -12,7 +12,7 @@
   /**
    * The data value.
    *
-   * @var boolean
+   * @var mixed
    */
   protected $value;
 
diff --git a/core/lib/Drupal/Core/TypedData/Type/Date.php b/core/lib/Drupal/Core/TypedData/Type/Date.php
deleted file mode 100644
index 078b8a0..0000000
--- a/core/lib/Drupal/Core/TypedData/Type/Date.php
+++ /dev/null
@@ -1,49 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\TypedData\Type\Date.
- */
-
-namespace Drupal\Core\TypedData\Type;
-
-use Drupal\Core\Datetime\DrupalDateTime;
-use Drupal\Core\TypedData\Primitive;
-use Drupal\Core\TypedData\Type\DateInterface;
-use InvalidArgumentException;
-
-/**
- * The date data type.
- *
- * The plain value of a date is an instance of the DrupalDateTime class. For
- * setting the value any value supported by the __construct() of the
- * DrupalDateTime class will work, including a DateTime object, a timestamp, a
- * string date, or an array of date parts.
- */
-class Date extends Primitive implements DateInterface {
-
-  /**
-   * The data value.
-   *
-   * @var DateTime
-   */
-  protected $value;
-
-  /**
-   * Overrides TypedData::setValue().
-   */
-  public function setValue($value, $notify = TRUE) {
-    // Notify the parent of any changes to be made.
-    if ($notify && isset($this->parent)) {
-      $this->parent->onChange($this->name);
-    }
-    // Don't try to create a date from an empty value.
-    // It would default to the current time.
-    if (!isset($value)) {
-      $this->value = $value;
-    }
-    else {
-      $this->value = $value instanceOf DrupalDateTime ? $value : new DrupalDateTime($value);
-    }
-  }
-}
diff --git a/core/lib/Drupal/Core/TypedData/Type/DateInterface.php b/core/lib/Drupal/Core/TypedData/Type/DateInterface.php
deleted file mode 100644
index c68454f..0000000
--- a/core/lib/Drupal/Core/TypedData/Type/DateInterface.php
+++ /dev/null
@@ -1,9 +0,0 @@
-<?php
-
-namespace Drupal\Core\TypedData\Type;
-
-use Drupal\Core\TypedData\PrimitiveInterface;
-
-interface DateInterface extends PrimitiveInterface {
-
-}
diff --git a/core/lib/Drupal/Core/TypedData/Type/DateTimeInterface.php b/core/lib/Drupal/Core/TypedData/Type/DateTimeInterface.php
new file mode 100644
index 0000000..cccc4c5
--- /dev/null
+++ b/core/lib/Drupal/Core/TypedData/Type/DateTimeInterface.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\Core\TypedData\Type;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+
+interface DateTimeInterface {
+
+  /**
+   * Returns the date time object.
+   *
+   * @return \Drupal\Core\Datetime\DrupalDateTime
+   *   A date object or NULL if there is no date.
+   */
+  public function getDateTime();
+
+  /**
+   * Sets the date time object.
+   *
+   * @param \Drupal\Core\Datetime\DrupalDateTime $dateTime
+   *   An instance of a date time object.
+   *
+   */
+  public function setDateTime(DrupalDateTime $dateTime);
+
+}
diff --git a/core/lib/Drupal/Core/TypedData/Type/DateTimeIso8601.php b/core/lib/Drupal/Core/TypedData/Type/DateTimeIso8601.php
new file mode 100644
index 0000000..18c2440
--- /dev/null
+++ b/core/lib/Drupal/Core/TypedData/Type/DateTimeIso8601.php
@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\TypedData\Type\Date.
+ */
+
+namespace Drupal\Core\TypedData\Type;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\Core\TypedData\Primitive;
+use Drupal\Core\TypedData\Type\DateTimeInterface;
+
+/**
+ * The date data type.
+ *
+ * The plain value of a date is an date string in the ISO 8601 format. For
+ * setting the value any value supported by the __construct() of the
+ * DrupalDateTime class will work, including a DateTime object, a
+ * string date, or an array of date parts.
+ */
+class DateTimeIso8601 extends Primitive implements StringInterface, DateTimeInterface {
+
+  /**
+   * The data value as a string in ISO 8601.
+   *
+   * @var string
+   */
+  protected $value;
+
+  /**
+   * Overrides TypedData::setValue().
+   */
+  public function setValue($value, $notify = TRUE) {
+    // Notify the parent of any changes to be made.
+    if ($notify && isset($this->parent)) {
+      $this->parent->onChange($this->name);
+    }
+    if ($value instanceof DrupalDateTime) {
+      $this->value = $value->format('c');
+    }
+    // Treat integer values as a UNIX Timestamp.
+    elseif ((string) (int) $value === (string) $value) {
+      $date_time = new DrupalDateTime($value);
+      $this->value = $date_time->format('c');
+    }
+    else {
+      $this->value = $value;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDateTime() {
+    if ($this->value) {
+      return new DrupalDateTime($this->value);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setDateTime(DrupalDateTime $dateTime) {
+    $this->value = $dateTime->format('c');
+  }
+}
diff --git a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/PrimitiveTypeConstraintValidator.php b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/PrimitiveTypeConstraintValidator.php
index d890720..603b08b 100644
--- a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/PrimitiveTypeConstraintValidator.php
+++ b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/PrimitiveTypeConstraintValidator.php
@@ -10,7 +10,7 @@
 use DateInterval;
 use Drupal\Core\TypedData\Type\BinaryInterface;
 use Drupal\Core\TypedData\Type\BooleanInterface;
-use Drupal\Core\TypedData\Type\DateInterface;
+use Drupal\Core\TypedData\Type\DateTimeInterface;
 use Drupal\Core\TypedData\Type\DurationInterface;
 use Drupal\Core\TypedData\Type\FloatInterface;
 use Drupal\Core\TypedData\Type\IntegerInterface;
@@ -40,8 +40,8 @@ public function validate($typed_data, Constraint $constraint) {
     elseif ($typed_data instanceof BooleanInterface) {
       $valid = is_bool($value) || $value === 0 || $value === '0' || $value === 1 || $value == '1';
     }
-    elseif ($typed_data instanceof DateInterface) {
-      $valid = $value instanceOf DrupalDateTime && !$value->hasErrors();
+    elseif ($typed_data instanceof DateTimeInterface) {
+      $valid = $typed_data->getDateTime() instanceOf DrupalDateTime && !$typed_data->getDateTime()->hasErrors();
     }
     elseif ($typed_data instanceof DurationInterface) {
       $valid = $value instanceof DateInterval;
diff --git a/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php b/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
index 2d14e5a..86f96bc 100644
--- a/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
+++ b/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
@@ -30,7 +30,7 @@ public function getPropertyDefinitions() {
 
     if (!isset(self::$propertyDefinitions)) {
       self::$propertyDefinitions['value'] = array(
-        'type' => 'date',
+        'type' => 'datetime',
         'label' => t('Date value'),
       );
     }
diff --git a/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataTest.php b/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataTest.php
index fca6f88..79f3521 100644
--- a/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataTest.php
@@ -134,18 +134,19 @@ public function testGetAndSet() {
     // Date type.
     $value = new DrupalDateTime();
     $typed_data = $this->createTypedData(array('type' => 'date'), $value);
-    $this->assertTrue($typed_data->getValue() === $value, 'Date value was fetched.');
+    $this->assertTrue($typed_data->getDateTime()->getTimestamp() == $value->getTimestamp(), 'Date value was fetched.');
+    $this->assertEqual($typed_data->getValue(), $typed_data->getDateTime()->format('c'), 'Value representation of a date is ISO 8061');
     $this->assertEqual($typed_data->validate()->count(), 0);
     $new_value = REQUEST_TIME + 1;
     $typed_data->setValue($new_value);
-    $this->assertTrue($typed_data->getValue()->getTimestamp() === $new_value, 'Date value was changed and set by timestamp.');
+    $this->assertTrue($typed_data->getDateTime()->getTimestamp() === $new_value, 'Date value was changed and set by timestamp.');
     $this->assertEqual($typed_data->validate()->count(), 0);
     $typed_data->setValue('2000-01-01');
-    $this->assertTrue($typed_data->getValue()->format('Y-m-d') == '2000-01-01', 'Date value was changed and set by date string.');
+    $this->assertTrue($typed_data->getDateTime()->format('Y-m-d') == '2000-01-01', 'Date value was changed and set by date string.');
     $this->assertTrue(is_string($typed_data->getString()), 'Date value was converted to string');
     $this->assertEqual($typed_data->validate()->count(), 0);
     $typed_data->setValue(NULL);
-    $this->assertNull($typed_data->getValue(), 'Date wrapper is null-able.');
+    $this->assertNull($typed_data->getDateTime(), 'Date wrapper is null-able.');
     $this->assertEqual($typed_data->validate()->count(), 0);
     $typed_data->setValue('invalid');
     $this->assertEqual($typed_data->validate()->count(), 1, 'Validation detected invalid value.');
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index eea7303..a212737 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -2197,7 +2197,7 @@ function system_data_type_info() {
     ),
     'date' => array(
       'label' => t('Date'),
-      'class' => '\Drupal\Core\TypedData\Type\Date',
+      'class' => '\Drupal\Core\TypedData\Type\DateTimeIso8601',
     ),
     'duration' => array(
       'label' => t('Duration'),