diff --git a/core/modules/taxonomy/src/Entity/Term.php b/core/modules/taxonomy/src/Entity/Term.php
index 655fa05..bf0f2cb 100644
--- a/core/modules/taxonomy/src/Entity/Term.php
+++ b/core/modules/taxonomy/src/Entity/Term.php
@@ -164,6 +164,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDescription(t('The parents of this term.'))
       ->setSetting('target_type', 'taxonomy_term')
       ->setCardinality(BaseFieldDefinition::CARDINALITY_UNLIMITED)
+      ->addConstraint('TaxonomyTermParent')
       ->setCustomStorage(TRUE);
 
     $fields['changed'] = BaseFieldDefinition::create('changed')
diff --git a/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraint.php b/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraint.php
new file mode 100644
index 0000000..d607e70
--- /dev/null
+++ b/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraint.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Drupal\taxonomy\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Validation constraint for changing the parent of a term in pending revisions.
+ *
+ * @Constraint(
+ *   id = "TaxonomyTermParent",
+ *   label = @Translation("Taxonomy term parent.", context = "Validation"),
+ * )
+ */
+class TaxonomyTermParentConstraint extends Constraint {
+
+  public $message = 'You can only change the parent for the <em>published</em> version of this term.';
+
+}
diff --git a/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraintValidator.php b/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraintValidator.php
new file mode 100644
index 0000000..86ddf9c
--- /dev/null
+++ b/core/modules/taxonomy/src/Plugin/Validation/Constraint/TaxonomyTermParentConstraintValidator.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\taxonomy\Plugin\Validation\Constraint;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+/**
+ * Constraint validator for changing term parents in pending revisions.
+ */
+class TaxonomyTermParentConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  private $entityTypeManager;
+
+  /**
+   * Creates a new TaxonomyTermParentConstraintValidator instance.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity_type.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($value, Constraint $constraint) {
+    $entity = !empty($value->getParent()) ? $value->getEntity() : NULL;
+
+    if ($entity && !$entity->isNew() && !$entity->isDefaultRevision()) {
+      $new_parents = array_column($value->getValue(), 'target_id');
+      $original_parents = array_keys($this->entityTypeManager->getStorage('taxonomy_term')->loadParents($entity->id()));
+      if ($new_parents != $original_parents) {
+        $this->context->addViolation($constraint->message);
+      }
+    }
+  }
+
+}
diff --git a/core/modules/taxonomy/src/TermForm.php b/core/modules/taxonomy/src/TermForm.php
index 1eae95a..4667dd7 100644
--- a/core/modules/taxonomy/src/TermForm.php
+++ b/core/modules/taxonomy/src/TermForm.php
@@ -3,6 +3,7 @@
 namespace Drupal\taxonomy;
 
 use Drupal\Core\Entity\ContentEntityForm;
+use Drupal\Core\Entity\EntityConstraintViolationListInterface;
 use Drupal\Core\Form\FormStateInterface;
 
 /**
@@ -118,6 +119,25 @@ public function buildEntity(array $form, FormStateInterface $form_state) {
   /**
    * {@inheritdoc}
    */
+  protected function getEditedFieldNames(FormStateInterface $form_state) {
+    return array_merge(['parent'], parent::getEditedFieldNames($form_state));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function flagViolations(EntityConstraintViolationListInterface $violations, array $form, FormStateInterface $form_state) {
+    // Manually flag violations of fields not handled by the form display.
+    foreach ($violations->getByField('parent') as $violation) {
+      $form_state->setErrorByName('parent', $violation->getMessage());
+    }
+
+    parent::flagViolations($violations, $form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function save(array $form, FormStateInterface $form_state) {
     $term = $this->entity;
 
diff --git a/core/modules/taxonomy/tests/src/Functional/TaxonomyTermContentModerationTest.php b/core/modules/taxonomy/tests/src/Functional/TaxonomyTermContentModerationTest.php
new file mode 100644
index 0000000..2d09f8e
--- /dev/null
+++ b/core/modules/taxonomy/tests/src/Functional/TaxonomyTermContentModerationTest.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\Tests\taxonomy\Functional;
+
+use Drupal\Core\Language\LanguageInterface;
+use Drupal\workflows\Entity\Workflow;
+
+/**
+ * Tests taxonomy terms with Content Moderation.
+ *
+ * @group content_moderation
+ * @group taxonomy
+ */
+class TaxonomyTermContentModerationTest extends TaxonomyTestBase {
+
+  /**
+   * The vocabulary used for creating terms.
+   *
+   * @var \Drupal\taxonomy\VocabularyInterface
+   */
+  protected $vocabulary;
+
+  /**
+   * Modules to install.
+   *
+   * @var array
+   */
+  public static $modules = ['node', 'taxonomy', 'content_moderation'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $this->drupalLogin($this->drupalCreateUser(['administer taxonomy', 'use editorial transition create_new_draft', 'use editorial transition publish']));
+
+    // Create a vocabulary.
+    $this->vocabulary = $this->createVocabulary();
+
+    // Set the vocabulary as moderated.
+    $workflow = Workflow::load('editorial');
+    $workflow->getTypePlugin()->addEntityTypeAndBundle('taxonomy_term', $this->vocabulary->id());
+    $workflow->save();
+  }
+
+  /**
+   * Tests taxonomy term parents on a moderated vocabulary.
+   */
+  public function testTaxonomyTermParents() {
+    // Create a simple hierarchy in the vocabulary, a root term and three parent
+    // terms.
+    $root = $this->createTerm($this->vocabulary, ['langcode' => 'en']);
+    $parent_1 = $this->createTerm($this->vocabulary, ['langcode' => 'en', 'parent' => $root->id()]);
+    $parent_2 = $this->createTerm($this->vocabulary, ['langcode' => 'en', 'parent' => $root->id()]);
+    $parent_3 = $this->createTerm($this->vocabulary, ['langcode' => 'en', 'parent' => $root->id()]);
+
+    // Create a child term and assign one of the parents above.
+    $child = $this->createTerm($this->vocabulary, ['langcode' => 'en', 'parent' => $parent_1->id()]);
+
+    $taxonomy_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');
+    $validation_message = 'You can only change the parent for the published version of this term.';
+
+    // Add a pending revision without changing the term parent.
+    $this->drupalGet('taxonomy/term/' . $child->id() . '/edit');
+    $this->drupalPostForm(NULL, [], 'Save and Create New Draft');
+
+    $this->assertSession()->pageTextNotContains($validation_message);
+
+    // Try to add a pending revision and change the parent.
+    $this->drupalGet('taxonomy/term/' . $child->id() . '/edit');
+    $this->drupalPostForm(NULL, [
+      'parent[]' => [$parent_2->id()],
+    ], 'Save and Create New Draft');
+
+    $this->assertSession()->pageTextContains($validation_message);
+  }
+
+}