diff --git a/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php b/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
index 719869c..658481e 100644
--- a/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
+++ b/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
@@ -530,6 +530,7 @@ class EntityReferenceBrowserWidget extends WidgetBase implements ContainerFactor
     return [
       '#theme_wrappers' => ['container'],
       '#attributes' => ['class' => $classes],
+      '#prefix' => '<p>' . $this->getCardinalityMessage($entities) . '</p>',
       'items' => array_map(
         function (ContentEntityInterface $entity, $row_id) use ($field_widget_display, $details_id, $field_parents, $replace_button_access) {
           $display = $field_widget_display->view($entity);
@@ -614,6 +615,42 @@ class EntityReferenceBrowserWidget extends WidgetBase implements ContainerFactor
     ];
   }
 
+  /**
+   * Generates a message informing the user how many more items they can choose.
+   *
+   * @param array|int $selected
+   *   The current selections, or how many items are selected.
+   *
+   * @return string
+   *   A message informing the user who many more items they can select.
+   */
+  protected function getCardinalityMessage($selected) {
+    $message = NULL;
+
+    $storage = $this->fieldDefinition->getFieldStorageDefinition();
+    $cardinality = $storage->getCardinality();
+    $target_type = $storage->getSetting('target_type');
+    $target_type = $this->entityTypeManager->getDefinition($target_type);
+
+    if (is_array($selected)) {
+      $selected = count($selected);
+    }
+
+    if ($cardinality === 1 && $selected === 0) {
+      $message = t('You can select one @entity_type.', [
+        '@entity_type' => $target_type->getSingularLabel(),
+      ]);
+    }
+    elseif ($cardinality >= $selected) {
+      $message = t('You can select up to @maximum @entity_type (@remaining left).', [
+        '@maximum' => $cardinality,
+        '@entity_type' => $target_type->getPluralLabel(),
+        '@remaining' => $cardinality - $selected,
+      ]);
+    }
+    return (string) $message;
+  }
+
   /**
    * Gets data that should persist across Entity Browser renders.
    *
diff --git a/src/Plugin/Field/FieldWidget/FileBrowserWidget.php b/src/Plugin/Field/FieldWidget/FileBrowserWidget.php
index d883f15..cde6471 100644
--- a/src/Plugin/Field/FieldWidget/FileBrowserWidget.php
+++ b/src/Plugin/Field/FieldWidget/FileBrowserWidget.php
@@ -217,6 +217,7 @@ class FileBrowserWidget extends EntityReferenceBrowserWidget {
     $current = [
       '#type' => 'table',
       '#empty' => $this->t('No files yet'),
+      '#prefix' => '<p>' . $this->getCardinalityMessage($entities) . '</p>',
       '#attributes' => ['class' => ['entities-list']],
       '#tabledrag' => [
         [
diff --git a/tests/src/FunctionalJavascript/EntityBrowserTest.php b/tests/src/FunctionalJavascript/EntityBrowserTest.php
index 857d2c1..2f0f8c3 100644
--- a/tests/src/FunctionalJavascript/EntityBrowserTest.php
+++ b/tests/src/FunctionalJavascript/EntityBrowserTest.php
@@ -50,6 +50,72 @@ class EntityBrowserTest extends EntityBrowserJavascriptTestBase {
     $this->assertSession()->linkExists('Select entities');
   }
 
+  /**
+   * Tests the field widget with a single-cardinality field.
+   */
+  public function testSingleCardinalityField() {
+    $this->container->get('entity_type.manager')
+      ->getStorage('field_storage_config')
+      ->load('node.field_reference')
+      ->setCardinality(1)
+      ->save();
+
+    // Create a file.
+    $image = $this->createFile('llama');
+
+    $this->drupalGet('node/add/article');
+
+    $this->assertSession()->linkExists('Select entities');
+    $this->assertSession()->pageTextContains('You can select one file.');
+    $this->getSession()->getPage()->clickLink('Select entities');
+
+    $this->getSession()->switchToIFrame('entity_browser_iframe_test_entity_browser_file');
+
+    $this->getSession()->getPage()->checkField('entity_browser_select[file:' . $image->id() . ']');
+    $this->getSession()->getPage()->pressButton('Select entities');
+
+    // Switch back to the main page.
+    $this->getSession()->switchToIFrame();
+    $this->waitForAjaxToFinish();
+    // A selection has been made, so the message is no longer necessary.
+    $this->assertSession()->pageTextNotContains('You can select one file.');
+  }
+
+  /**
+   * Tests the field widget with a multi-cardinality field.
+   */
+  public function testMultiCardinalityField() {
+    $this->container->get('entity_type.manager')
+      ->getStorage('field_storage_config')
+      ->load('node.field_reference')
+      ->setCardinality(3)
+      ->save();
+
+    // Create a few files to choose.
+    $images = [];
+    array_push($images, $this->createFile('llama'));
+    array_push($images, $this->createFile('sloth'));
+    array_push($images, $this->createFile('puppy'));
+
+    $this->drupalGet('node/add/article');
+
+    $this->assertSession()->linkExists('Select entities');
+    $this->assertSession()->pageTextContains('You can select up to 3 file entities (3 left).');
+    $this->getSession()->getPage()->clickLink('Select entities');
+
+    $this->getSession()->switchToIFrame('entity_browser_iframe_test_entity_browser_file');
+
+    $this->getSession()->getPage()->checkField('entity_browser_select[file:' . $images[0]->id() . ']');
+    $this->getSession()->getPage()->checkField('entity_browser_select[file:' . $images[1]->id() . ']');
+    $this->getSession()->getPage()->pressButton('Select entities');
+
+    // Switch back to the main page.
+    $this->getSession()->switchToIFrame();
+    $this->waitForAjaxToFinish();
+    // Selections have been made, so the message should be different.
+    $this->assertSession()->pageTextContains('You can select up to 3 file entities (1 left).');
+  }
+
   /**
    * Tests tabs widget selector.
    */