diff --git a/src/Entity/MediaBundle.php b/src/Entity/MediaBundle.php
index 8833f82..1a9d5f8 100644
--- a/src/Entity/MediaBundle.php
+++ b/src/Entity/MediaBundle.php
@@ -2,8 +2,9 @@
 
 namespace Drupal\media_entity\Entity;
 
-use Drupal\Core\Entity\EntityDescriptionInterface;
 use Drupal\Core\Config\Entity\ConfigEntityBundleBase;
+use Drupal\Core\Entity\EntityDescriptionInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
 use Drupal\Core\Plugin\DefaultSingleLazyPluginCollection;
 use Drupal\media_entity\MediaBundleInterface;
@@ -121,7 +122,7 @@ class MediaBundle extends ConfigEntityBundleBase implements MediaBundleInterface
   /**
    * Default status of this media bundle.
    *
-   * @var array
+   * @var bool
    */
   public $status = TRUE;
 
@@ -241,4 +242,17 @@ class MediaBundle extends ConfigEntityBundleBase implements MediaBundleInterface
     $this->new_revision = $new_revision;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
+    parent::postSave($storage, $update);
+
+    if (!$update) {
+      // Inform the plugin that this bundle has just been created.
+      $this->getType()->onBundleSave($this->id());
+    }
+
+  }
+
 }
diff --git a/src/MediaBundleForm.php b/src/MediaBundleForm.php
index 014a538..5d310f0 100644
--- a/src/MediaBundleForm.php
+++ b/src/MediaBundleForm.php
@@ -373,7 +373,7 @@ class MediaBundleForm extends EntityForm {
 
     // Override the "status" base field default value, for this bundle.
     $fields = $this->entityFieldManager->getFieldDefinitions('media', $bundle->id());
-    $media = $this->entityTypeManager->getStorage('media')->create(array('bundle' => $bundle->id()));
+    $media = $this->entityTypeManager->getStorage('media')->create(['bundle' => $bundle->id()]);
     $value = (bool) $form_state->getValue(['options', 'status']);
     if ($media->status->value != $value) {
       $fields['status']->getConfig($bundle->id())->setDefaultValue($value)->save();
diff --git a/src/MediaTypeBase.php b/src/MediaTypeBase.php
index a472e7d..b2da7e8 100644
--- a/src/MediaTypeBase.php
+++ b/src/MediaTypeBase.php
@@ -3,14 +3,14 @@
 namespace Drupal\media_entity;
 
 use Drupal\Component\Plugin\PluginBase;
+use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Config\Config;
 use Drupal\Core\Entity\EntityFieldManagerInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
-use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
-use Drupal\Component\Utility\NestedArray;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Symfony\Component\DependencyInjection\ContainerInterface;
-use Drupal\Core\Form\FormStateInterface;
 
 /**
  * Base implementation of media type plugin.
@@ -158,4 +158,9 @@ abstract class MediaTypeBase extends PluginBase implements MediaTypeInterface, C
     return 'media:' . $media->bundle() . ':' . $media->uuid();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function onBundleSave($bundle_name) {}
+
 }
diff --git a/src/MediaTypeInterface.php b/src/MediaTypeInterface.php
index 2a171c2..09ca4c4 100644
--- a/src/MediaTypeInterface.php
+++ b/src/MediaTypeInterface.php
@@ -2,8 +2,8 @@
 
 namespace Drupal\media_entity;
 
-use Drupal\Component\Plugin\PluginInspectionInterface;
 use Drupal\Component\Plugin\ConfigurablePluginInterface;
+use Drupal\Component\Plugin\PluginInspectionInterface;
 use Drupal\Core\Plugin\PluginFormInterface;
 
 /**
@@ -85,4 +85,12 @@ interface MediaTypeInterface extends PluginInspectionInterface, ConfigurablePlug
    */
   public function getDefaultName(MediaInterface $media);
 
+  /**
+   * Take actions when saving a bundle.
+   *
+   * @param string $bundle_name
+   *   The machine-name of the bundle saved.
+   */
+  public function onBundleSave($bundle_name);
+
 }
diff --git a/src/MediaTypeSourceFieldTrait.php b/src/MediaTypeSourceFieldTrait.php
new file mode 100644
index 0000000..7067882
--- /dev/null
+++ b/src/MediaTypeSourceFieldTrait.php
@@ -0,0 +1,233 @@
+<?php
+
+namespace Drupal\media_entity;
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+
+/**
+ * To exhibit by derivatives of Drupal\media_entity\MediaTypeBase.
+ *
+ * Implements most of the behavior required for a single source field that may
+ * be populated with a default field upon creation of a bundle.
+ *
+ * You will need to add a source_field key to your configuration schema and
+ * annotate your class with the MediaTypeSourceField annotation.
+ */
+trait MediaTypeSourceFieldTrait {
+
+  /**
+   * The default source field name.
+   *
+   * @var string
+   */
+  protected $defaultSourceFieldName;
+
+  /**
+   * Ensures the t() method is available.
+   *
+   * @see \Drupal\Core\StringTranslation\StringTranslationTrait
+   */
+  abstract protected function t($string, array $args = [], array $options = []);
+
+  /**
+   * Provide information related to source field configuration.
+   *
+   * This includes information about a default field, a field that will be
+   * created automatically if the user does not disable the automatich creation.
+   *
+   * @return array[array]
+   *   An array containing keys identifying information regarding the source
+   *   field configuration:
+   *   - allowed_types: array of strings specifying field types that are
+   *     acceptable as source field types.
+   *   - default_type: string identifying the default field type.
+   *   - default_label: string that will be used for the label for the default
+   *     field.
+   *   - default_widget: string identifying the form widget for the default
+   *     field.
+   *   - default_formatter: string identifying the formatter to be used in the
+   *     display.
+   *   - field_storage_extra_config: (optional) array with extra keys to be
+   *     passed to FieldStorageConfig::create().
+   *   - field_extra_config: (optional) array with extra keys to be passed to
+   *     FieldConfig::create().
+   */
+  abstract protected function sourceFieldInfo();
+
+  /**
+   * Produce a form fragment to configure the source field.
+   *
+   * To be called from a media type's buildConfigurationForm() method.
+   *
+   * @param array $form
+   *   The $form array as passed to the buildConfigurationForm().
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The $form_state instance.
+   *
+   * @return array
+   *   The form element to be used in the configuration form.
+   */
+  protected function sourceFieldConfigurationForm(array $form, FormStateInterface $form_state) {
+    $source_field_info = $this->sourceFieldInfo();
+    $options = [];
+
+    $allowed_field_types = $source_field_info['allowed_types'];
+    /** @var \Drupal\media_entity\MediaBundleInterface $bundle */
+    $bundle = $form_state->getFormObject()->getEntity();
+    foreach ($this->entityFieldManager->getFieldDefinitions('media', $bundle->id()) as $field_name => $field) {
+      $allowed_type = in_array($field->getType(), $allowed_field_types);
+      $is_base_field = $field->getFieldStorageDefinition()->isBaseField();
+      if ($allowed_type && !$is_base_field) {
+        $options[$field_name] = $field->getLabel();
+      }
+    }
+
+    // Add a checkbox to allow the field being created automatically on save.
+    // Only include it when the bundle is new, so we can use its presence to
+    // know we can safely override the source field configuration.
+    if ($bundle->isNew()) {
+      $form['create_source_field'] = [
+        '#type' => 'checkbox',
+        '#title' => $this->t('Create a source field automatically when saving this form.'),
+        '#description' => $this->t('If checked, a default field will be created and used as a source field. If you uncheck the field, you will need to create a field and revisit this form later to select it.'),
+        '#default_value' => TRUE,
+      ];
+    }
+
+    // Select the source field. Only show it when the bundle is not new, so
+    // there will potentially be fields to select.
+    $form['source_field'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Field with source information'),
+      '#default_value' => isset($this->configuration['source_field']) ? $this->configuration['source_field'] : '',
+      '#empty_option' => $this->t('- None -'),
+      '#empty_value' => '',
+      '#options' => $options,
+      '#access' => !$bundle->isNew(),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function onBundleSave($bundle_name) {
+    // If we are creating a new bundle and the user elected to have the default
+    // field created, defaultSourceFieldName will have been set from
+    // setConfiguration() and determineDefaultSourceFieldName().
+    // @see determineDefaultSourceFieldName()
+    if (isset($this->defaultSourceFieldName)) {
+      $this->createDefaultSourceField($bundle_name);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createDefaultSourceField($bundle_name) {
+    $source_field_info = $this->sourceFieldInfo();
+
+    if (!in_array($source_field_info['default_type'], $source_field_info['allowed_types'])) {
+      throw new \LogicException('Default source field type is not within the allowed field types.');
+    }
+
+    $field_name = $this->defaultSourceFieldName;
+
+    $storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'media',
+      'type' => $source_field_info['default_type'],
+    ]);
+    $storage->save();
+
+    // Create the field instance.
+    FieldConfig::create([
+      'entity_type' => 'media',
+      'field_name' => $field_name,
+      'label' => $source_field_info['default_label'],
+      'required' => TRUE,
+      'bundle' => $bundle_name,
+    ])->save();
+
+    // Make the field visible on the form display.
+    /** @var \Drupal\Core\Entity\Display\EntityFormDisplayInterface $form_display */
+    $form_display = EntityFormDisplay::create([
+      'targetEntityType' => 'media',
+      'bundle' => $bundle_name,
+      'mode' => 'default',
+      'status' => TRUE,
+    ]);
+    $form_display->setComponent($field_name, [
+      'type' => $source_field_info['default_widget'],
+    ])->save();
+
+    // Make the field visible on the media entity itself.
+    /** @var \Drupal\Core\Entity\Display\EntityViewDisplayInterface $display */
+    $display = EntityViewDisplay::create([
+      'targetEntityType' => 'media',
+      'bundle' => $bundle_name,
+      'mode' => 'default',
+      'status' => TRUE,
+    ]);
+    $display->setComponent($field_name, [
+      'type' => $source_field_info['default_formatter'],
+    ])->save();
+  }
+
+  /**
+   * Determine a free field name to use as the default field.
+   *
+   * @return string
+   *   An appropriate field name that was determined to be available.
+   */
+  protected function determineDefaultSourceFieldName() {
+    // Determine a unique field name.
+    if (isset($this->defaultSourceFieldName)) {
+      return $this->defaultSourceFieldName;
+    }
+
+    $base_field_name = 'field_media_' . $this->getPluginId();
+    $field_name_candidate = $base_field_name;
+    $postfix = '';
+    while (FieldStorageConfig::loadByName('media', $field_name_candidate)) {
+      if (empty($postfix)) {
+        $postfix = 1;
+      }
+      else {
+        $postfix++;
+      }
+
+      $field_name_candidate = $base_field_name . '_' . $postfix;
+    }
+
+    $this->defaultSourceFieldName = $field_name_candidate;
+
+    return $this->defaultSourceFieldName;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setConfiguration(array $configuration) {
+    // Take out the create_source_field key when present so it doesn't end up
+    // in the configuration. Record it was set so we can later decide to
+    // actually create the field. Determine the field name here so it correctly
+    // is entered into the configuration.
+    if (isset($configuration['create_source_field'])) {
+      $create_source_field = $configuration['create_source_field'];
+      unset($configuration['create_source_field']);
+
+      if ($create_source_field) {
+        $configuration['source_field'] = $this->determineDefaultSourceFieldName();
+      }
+    }
+
+    parent::setConfiguration($configuration);
+  }
+
+}
diff --git a/src/Plugin/Action/DeleteMedia.php b/src/Plugin/Action/DeleteMedia.php
index b2a98d2..4a5a48e 100644
--- a/src/Plugin/Action/DeleteMedia.php
+++ b/src/Plugin/Action/DeleteMedia.php
@@ -84,7 +84,7 @@ class DeleteMedia extends ActionBase implements ContainerFactoryPluginInterface
    * {@inheritdoc}
    */
   public function execute($object = NULL) {
-    $this->executeMultiple(array($object));
+    $this->executeMultiple([$object]);
   }
 
   /**
diff --git a/tests/modules/media_entity_test_type/config/schema/media_entity_test_type.schema.yml b/tests/modules/media_entity_test_type/config/schema/media_entity_test_type.schema.yml
index 6ff7e14..257c840 100644
--- a/tests/modules/media_entity_test_type/config/schema/media_entity_test_type.schema.yml
+++ b/tests/modules/media_entity_test_type/config/schema/media_entity_test_type.schema.yml
@@ -5,3 +5,6 @@ media_entity.bundle.type.test_type:
     test_config_value:
       type: string
       label: 'Test config value'
+    source_field:
+      type: string
+      label: 'Source field'
diff --git a/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php b/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
index 60d68a0..d34114d 100644
--- a/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
+++ b/tests/modules/media_entity_test_type/src/Plugin/MediaEntity/Type/TestType.php
@@ -2,7 +2,12 @@
 
 namespace Drupal\media_entity_test_type\Plugin\MediaEntity\Type;
 
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\media_entity\MediaTypeSourceFieldTrait;
 use Drupal\media_entity\Plugin\MediaEntity\Type\Generic;
 
 /**
@@ -15,6 +20,20 @@ use Drupal\media_entity\Plugin\MediaEntity\Type\Generic;
  * )
  */
 class TestType extends Generic {
+  use MediaTypeSourceFieldTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function sourceFieldInfo() {
+    return [
+      'allowed_types' => ['string'],
+      'default_label' => $this->t('Test source'),
+      'default_type' => 'string',
+      'default_widget' => 'string_textfield',
+      'default_formatter' => 'string',
+    ];
+  }
 
   /**
    * {@inheritdoc}
@@ -45,6 +64,10 @@ class TestType extends Generic {
       '#default_value' => empty($this->configuration['test_config_value']) ? NULL : $this->configuration['test_config_value'],
     ];
 
+    $form = $this->sourceFieldConfigurationForm($form, $form_state);
+
+    $form['source_field']['#description'] = $this->t('Field on media entity that stores the source information.');
+
     return $form;
   }
 
diff --git a/tests/src/FunctionalJavascript/BundleCreationTest.php b/tests/src/FunctionalJavascript/BundleCreationTest.php
new file mode 100644
index 0000000..385e79d
--- /dev/null
+++ b/tests/src/FunctionalJavascript/BundleCreationTest.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace Drupal\Tests\media_entity\FunctionalJavascript;
+
+/**
+ * Tests the media bundle creation.
+ *
+ * @group media_entity
+ */
+class BundleCreationTest extends MediaEntityJavascriptTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = [
+    'media_entity_test_type',
+  ];
+
+  /**
+   * Tests the media bundle creation form.
+   */
+  public function testBundleCreationFormWithDefaultField() {
+    $label = 'Bundle with Default Field';
+    $bundleMachineName = str_replace(' ', '_', strtolower($label));
+
+    $this->drupalGet('admin/structure/media/add');
+    $page = $this->getSession()->getPage();
+
+    // Fill in a label to the bundle.
+    $page->fillField('label', $label);
+    // Wait for machine name generation. Default: waitUntilVisible(), does not
+    // work properly.
+    $this->getSession()
+      ->wait(5000, "jQuery('.machine-name-value').text() === '{$bundleMachineName}'");
+
+    // Select our test bundle type.
+    $this->assertSession()->fieldExists('Type provider');
+    $this->assertSession()->optionExists('Type provider', 'test_type');
+    $page->selectFieldOption('Type provider', 'test_type');
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
+    // Make sure the checkbox for creating the source field is there and save.
+    $this->assertSession()
+      ->checkboxChecked('type_configuration[test_type][create_source_field]');
+    $page->pressButton('Save media bundle');
+
+    // Check whether the source field was correctly created.
+    $this->drupalGet("admin/structure/media/manage/{$bundleMachineName}/fields");
+
+    // Check 2nd column of first data row, to be machine name for field name.
+    $this->assertSession()
+      ->elementContains('xpath', '(//table[@id="field-overview"]//tr)[2]//td[2]', 'field_media_test_type');
+    // Check 3rd column of first data row, to be correct field type.
+    $this->assertSession()
+      ->elementTextContains('xpath', '(//table[@id="field-overview"]//tr)[2]//td[3]', 'Text (plain)');
+
+    // Check that the source field is correctly assigned to media bundle.
+    $this->drupalGet("admin/structure/media/manage/{$bundleMachineName}");
+
+    $this->assertSession()
+      ->fieldValueEquals('type_configuration[test_type][source_field]', 'field_media_test_type');
+  }
+
+  /**
+   * Test creation of media bundle without default field.
+   */
+  public function testBundleCreationWithoutDefaultField() {
+    $label = 'Bundle without Default Field';
+    $bundleMachineName = str_replace(' ', '_', strtolower($label));
+
+    $this->drupalGet('admin/structure/media/add');
+    $page = $this->getSession()->getPage();
+
+    // Fill in a label to the bundle.
+    $page->fillField('label', 'Bundle without Default Field');
+
+    // Wait for machine name generation. Default: waitUntilVisible(), does not
+    // work properly.
+    $this->getSession()
+      ->wait(5000, "jQuery('.machine-name-value').text() === '{$bundleMachineName}'");
+
+    // Select our test bundle type.
+    $this->assertSession()->fieldExists('Type provider');
+    $this->assertSession()->optionExists('Type provider', 'test_type');
+    $page->selectFieldOption('Type provider', 'test_type');
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
+    // Un-check creation of default source field.
+    $page->uncheckField('type_configuration[test_type][create_source_field]');
+    $page->pressButton('Save media bundle');
+
+    // Check that there are not fields created.
+    $this->drupalGet("admin/structure/media/manage/{$bundleMachineName}/fields");
+    $this->assertSession()
+      ->elementsCount('xpath', '//*[text()="No fields are present yet."]', 1);
+  }
+
+}