diff -u b/config/schema/paragraphs_collection.schema.yml b/config/schema/paragraphs_collection.schema.yml
--- b/config/schema/paragraphs_collection.schema.yml
+++ b/config/schema/paragraphs_collection.schema.yml
@@ -1,24 +1,19 @@
 paragraphs.behavior.settings.style:
   type: paragraphs.behavior.settings_base
   mapping:
-    group:
-      type: string
-      label: Style group
     groups:
       type: sequence
       label: 'Style groups'
       sequence:
-        type: string
-        label: 'Group name'
+        type: mapping
+        label: 'Style groups configuration'
+        mapping:
+          default:
+            type: string
+            label: 'Default group style'
     default:
       type: string
       label: Default style
-    defaults:
-      type: sequence
-      label: 'Default styles'
-      sequence:
-        type: string
-        label: 'Style name'
 
 paragraphs.behavior.settings.grid_layout:
   type: paragraphs.behavior.settings_base
diff -u b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
--- b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
+++ b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
@@ -10,10 +10,10 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\paragraphs\Entity\Paragraph;
-use Drupal\paragraphs\Entity\ParagraphsType;
 use Drupal\paragraphs\ParagraphInterface;
 use Drupal\paragraphs\ParagraphsBehaviorBase;
 use Drupal\paragraphs_collection\StyleDiscoveryInterface;
+use Drupal\paragraphs_collection\StyleGroupDiscoveryInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -37,6 +37,13 @@
     */
    protected $yamlStyleDiscovery;
 
+  /**
+   * The yaml style group discovery.
+   *
+   * @var \Drupal\paragraphs_collection\StyleGroupDiscovery
+   */
+  protected $yamlStyleGroupDiscovery;
+
    /**
     * Constructs a new SelectionBase object.
     *
@@ -50,10 +57,13 @@
     *   The entity field manager.
     * @param \Drupal\paragraphs_collection\StyleDiscoveryInterface $yaml
     *   The yaml style discovery.
+    * @param \Drupal\paragraphs_collection\StyleGroupDiscoveryInterface $style_group_discovery
+    *   The yaml style group discovery.
     */
-   public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityFieldManager $entity_field_manager, StyleDiscoveryInterface $yaml) {
+   public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityFieldManager $entity_field_manager, StyleDiscoveryInterface $yaml, StyleGroupDiscoveryInterface $style_group_discovery) {
      parent::__construct($configuration, $plugin_id, $plugin_definition, $entity_field_manager);
      $this->yamlStyleDiscovery = $yaml;
+     $this->yamlStyleGroupDiscovery = $style_group_discovery;
    }
 
    /**
@@ -62,7 +72,8 @@
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
      return new static($configuration, $plugin_id, $plugin_definition,
        $container->get('entity_field.manager'),
-       $container->get('paragraphs_collection.style_discovery')
+       $container->get('paragraphs_collection.style_discovery'),
+       $container->get('paragraphs_collection.style_group_discovery')
      );
    }
 
@@ -81,38 +92,21 @@
         'id' => $wrapper_id,
       ],
     ];
-
-    if (count($this->configuration['groups']) != 0) {
-      foreach ($this->configuration['groups'] as $group) {
-        $group_id = strtolower(str_replace(' ', '_', $group));
-        $plugin_default = '';
-        if (isset($this->configuration['defaults'][$group_id])) {
-          $plugin_default = $this->configuration['defaults'][$group_id];
-        }
-        $form['style_wrapper'][$group_id] = [
-          '#type' => 'select',
-          '#title' => !empty($this->configuration['groups'][$group]) ? t('%group Style', ['%group' => $this->configuration['groups'][$group]]) : t('Style'),
-          '#options' => $this->getStyleOptions($group, $plugin_default),
-          '#default_value' => $paragraph->getBehaviorSetting($this->getPluginId(), $group_id, $this->configuration['default']),
-          '#attributes' => ['class' => ['paragraphs-style']],
-        ];
-        // Allow empty option in case there is no default style configured.
-        if (!isset($this->configuration['defaults'][$group_id])) {
-          $form['style_wrapper'][$group_id]['#empty_option'] = $this->t('- Default -');
-        }
+    foreach ($this->configuration['groups'] as $group_id => $default) {
+      $plugin_default = '';
+      if (isset($this->configuration['groups'][$group_id]['default'])) {
+        $plugin_default = $this->configuration['groups'][$group_id]['default'];
       }
-    }
-    else {
-      $form['style_wrapper']['style'] = [
+      $form['style_wrapper']['styles'][$group_id] = [
         '#type' => 'select',
-        '#title' => !empty($this->configuration['group']) ? t('%group Style', ['%group' => $this->configuration['group']]) : t('Style'),
-        '#options' => $this->getStyleOptions($this->configuration['group'], $this->configuration['default']),
-        '#default_value' => $paragraph->getBehaviorSetting($this->getPluginId(), 'style', $this->configuration['default']),
+        '#title' => $this->t('%group Style', ['%group' => $this->yamlStyleGroupDiscovery->getGroupLabel($group_id)]),
+        '#options' => $this->getStyleOptions($group_id, $plugin_default),
+        '#default_value' => $paragraph->getBehaviorSetting($this->getPluginId(), $group_id, $this->configuration['groups'][$group_id]['default']),
         '#attributes' => ['class' => ['paragraphs-style']],
       ];
       // Allow empty option in case there is no default style configured.
-      if (!$this->configuration['default']) {
-        $form['style_wrapper']['style']['#empty_option'] = $this->t('- Default -');
+      if (empty($plugin_default)) {
+        $form['style_wrapper']['styles'][$group_id]['#empty_option'] = $this->t('- Default -');
       }
     }
 
@@ -155,11 +149,11 @@
     $form['groups'] = [
       '#type' => 'select',
       '#title' => $this->t('Style groups'),
+      '#required' => TRUE,
       '#multiple' => TRUE,
-      '#empty_option' => $this->t('- None -'),
-      '#options' => $this->yamlStyleDiscovery->getStyleGroups(),
-      '#description' => $this->t('Restrict available styles to a certain style group. Select "- None -" to allow all styles.'),
-      '#default_value' => $this->configuration['groups'],
+      '#options' => $this->yamlStyleGroupDiscovery->getStyleGroups(),
+      '#description' => $this->t('Restrict available styles to a certain style group. Select none to allow all styles.'),
+      '#default_value' => array_keys($this->configuration['groups']),
       '#ajax' => [
         'callback' => [$this, 'updateDefaultStyle'],
         'wrapper' => 'style-wrapper',
@@ -168,38 +162,25 @@
     // @todo: Remove getCompleteFormState() after https://www.drupal.org/project/drupal/issues/2798261.
     $group_key = ['behavior_plugins', $this->getPluginId(), 'settings', 'groups'];
     $groups = $form_state->getCompleteFormState()->getValue($group_key, $this->configuration['groups']);
-    if (count($groups) != 0) {
-      $form['defaults'] = [
-        '#type' => 'container',
-        '#prefix' => '<div id="style-wrapper">',
-        '#suffix' => '</div>',
-      ];
-      foreach($groups as $group) {
-        $default = '';
-        $group_name = strtolower(str_replace(' ', '_', $group));
-        if (isset($this->configuration['defaults'][$group_name])) {
-          $default = $this->configuration['defaults'][$group_name];
-        }
-        $form['defaults'][$group_name] = [
-          '#type' => 'select',
-          '#title' => $this->t($group . ' default style'),
-          '#empty_option' => $this->t('- None -'),
-          '#options' => $this->yamlStyleDiscovery->getStyleOptions($group),
-          '#description' => $this->t('This style will be default option on a behavior form.'),
-          '#default_value' => $default,
-        ];
+    $form['groups_defaults'] = [
+      '#type' => 'container',
+      '#prefix' => '<div id="style-wrapper">',
+      '#suffix' => '</div>',
+    ];
+
+    foreach ($groups as $group_id => $group_default) {
+      $default = '';
+      if (!empty($this->configuration['groups'][$group_id]['default'])) {
+        $default = $this->configuration['groups'][$group_id]['default'];
       }
-    }
-    else {
-      $form['default'] = [
+      $group_label = $this->yamlStyleGroupDiscovery->getGroupLabel($group_id);
+      $form['groups_defaults'][$group_id]['default'] = [
         '#type' => 'select',
+        '#title' => $this->t($group_label . ' default style'),
         '#empty_option' => $this->t('- None -'),
-        '#options' => $this->yamlStyleDiscovery->getStyleOptions(reset($groups)),
-        '#title' => $this->t('Default style'),
+        '#options' => $this->yamlStyleDiscovery->getStyleOptions($group_id),
         '#description' => $this->t('This style will be default option on a behavior form.'),
-        '#default_value' => $this->configuration['default'],
-        '#prefix' => '<div id="style-wrapper">',
-        '#suffix' => '</div>',
+        '#default_value' => $default,
       ];
     }
 
@@ -211,15 +192,9 @@
    */
   public static function updateDefaultStyle(array $form, FormStateInterface $form_state) {
     $group_select = $form_state->getTriggeringElement();
-    $groups = $form_state->getValue($group_select['#array_parents']);
     // Gets the behavior plugin settings form.
     $settings_form = NestedArray::getValue($form, array_slice($group_select['#array_parents'], 0, -1));
-    if (count($groups) != 0) {
-      return $settings_form['defaults'];
-    }
-    else {
-      return $settings_form['default'];
-    }
+    return $settings_form['groups_defaults'];
   }
 
   /**
@@ -236,10 +211,7 @@
    * {@inheritdoc}
    */
   public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
-    $this->configuration['group'] = $form_state->getValue('group');
-    $this->configuration['groups'] = $form_state->getValue('groups');
-    $this->configuration['default'] = $form_state->getValue('default');
-    $this->configuration['defaults'] = $form_state->getValue('defaults') ?: [];
+    $this->configuration['groups'] = $form_state->getValue('groups_defaults');
   }
 
   /**
@@ -247,10 +219,7 @@
    */
   public function defaultConfiguration() {
     return [
-      'group' => '',
       'groups' => [],
-      'default' => '',
-      'defaults' => [],
     ];
   }
 
@@ -261,29 +230,11 @@
     // In case the current style is not set, fallback to the default style.
     // If default style is set to none, no style will be applied.
     $paragraph_styles = [];
-    if (!empty($this->configuration['defaults'])) {
-      foreach ($this->configuration['defaults'] as $key => $value) {
-        $paragraph_styles[$key] = $paragraph->getBehaviorSetting($this->getPluginId(), $key, $this->configuration['defaults'][$key]);
-      }
-      foreach ($paragraph_styles as $key => $value) {
-        $style = $this->yamlStyleDiscovery->getStyle($value, $this->configuration['defaults'][$key]);
-        if ($style) {
-          $build['#attributes']['class'][] = 'paragraphs-behavior-' . $this->getPluginId() . '--' . $style['name'];
-          if (!isset($build['#attached']['library'])) {
-            $build['#attached']['library'] = [];
-          }
-          $build['#attached']['library'] = array_merge($style['libraries'], $build['#attached']['library']);
-
-          // Add CSS classes from style configuration if they are defined.
-          if (!empty($style['classes'])) {
-            $build['#attributes']['class'] = array_merge($style['classes'], $build['#attributes']['class']);
-          }
-        }
-      }
+    foreach ($this->configuration['groups'] as $key => $value) {
+      $paragraph_styles[$key] = $paragraph->getBehaviorSetting($this->getPluginId(), ['styles', $key], $this->configuration['groups'][$key]['default']);
     }
-    else {
-      $paragraph_style = $paragraph->getBehaviorSetting($this->getPluginId(), 'style', $this->configuration['default']);
-      $style = $this->yamlStyleDiscovery->getStyle($paragraph_style, $this->configuration['default']);
+    foreach ($paragraph_styles as $key => $value) {
+      $style = $this->yamlStyleDiscovery->getStyle($value, $this->configuration['groups'][$key]['default']);
       if ($style) {
         $build['#attributes']['class'][] = 'paragraphs-behavior-' . $this->getPluginId() . '--' . $style['name'];
         if (!isset($build['#attached']['library'])) {
@@ -297,7 +248,6 @@
         }
       }
     }
-
   }
 
    /**
@@ -352,25 +302,13 @@
    */
   public static function getStyleTemplate(ParagraphInterface $paragraph) {
     if ($paragraph->getParagraphType()->hasEnabledBehaviorPlugin('style')) {
-      if ($defaults = $paragraph->getParagraphType()->getBehaviorPlugin('style')->getConfiguration()['defaults']) {
-        if ($paragraph_style = $paragraph->getBehaviorSetting('style', 'style', reset($defaults))) {
-          $style = \Drupal::service('paragraphs_collection.style_discovery')
-            ->getStyle($paragraph_style);
-          if (!empty($style['template'])) {
-            return $style['template'];
-          }
-        };
-      }
-      else {
-        $default = $paragraph->getParagraphType()->getBehaviorPlugin('style')->getConfiguration()['default'];
-        if ($paragraph_style = $paragraph->getBehaviorSetting('style', 'style', $default)) {
-          $style = \Drupal::service('paragraphs_collection.style_discovery')
-            ->getStyle($paragraph_style);
-          if (!empty($style['template'])) {
-            return $style['template'];
-          }
-        };
-      }
+      $defaults = $paragraph->getParagraphType()->getBehaviorPlugin('style')->getConfiguration()['groups'];
+      if ($paragraph_style = $paragraph->getBehaviorSetting('style', ['styles', key($defaults)], reset($defaults)['default'])) {
+        $style = \Drupal::service('paragraphs_collection.style_discovery')->getStyle($paragraph_style);
+        if (!empty($style['template'])) {
+          return $style['template'];
+        }
+      };
     }
   }
 
diff -u b/src/Tests/ParagraphsStylePluginTest.php b/src/Tests/ParagraphsStylePluginTest.php
--- b/src/Tests/ParagraphsStylePluginTest.php
+++ b/src/Tests/ParagraphsStylePluginTest.php
@@ -49,11 +49,15 @@
     $this->fieldUIAddExistingField('admin/structure/paragraphs_type/' . $paragraph_type, 'paragraphs_text', $paragraph_type);
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $this->assertFieldByName('behavior_plugins[style][settings][groups][]');
-    $this->assertFieldByName('behavior_plugins[style][settings][default]', '');
     $edit = [
       'behavior_plugins[style][enabled]' => TRUE,
       'behavior_plugins[style][settings][groups][]' => [],
-      'behavior_plugins[style][settings][default]' => '',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('Style groups field is required.');
+    $edit = [
+      'behavior_plugins[style][enabled]' => TRUE,
+      'behavior_plugins[style][settings][groups][]' => ['regular_test_group'],
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
 
@@ -65,44 +69,22 @@
     $this->assertText('Style');
     $this->assertField('paragraphs[0][behavior_plugins][style][style_wrapper][style]');
 
-    // Check that a style without a style group is available.
-    $options = $this->xpath('//select[@name=:name]//option[normalize-space(text())=:text]', [
-      ':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][style]',
-      ':text' => 'Groupless',
-    ]);
-    $this->assertTrue(isset($options[0]), 'Groupless style available.');
-
     // Check that the style options are sorted alphabetically.
     $styles = $this->xpath('//select[contains(@id, :id)]', [':id' => 'edit-paragraphs-0-behavior-plugins-style-style']);
     $this->assertEqual('- Default -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
-    $this->assertEqual('Groupless', $styles[0]->option[2]);
-    $this->assertEqual('Italic', $styles[0]->option[3]);
-    $this->assertEqual('Regular', $styles[0]->option[4]);
-    $this->assertEqual('Underline', $styles[0]->option[5]);
+    $this->assertEqual('Regular', $styles[0]->option[2]);
 
     // Restrict the paragraphs type to the "Italic Test Group" style group.
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $this->assertFieldByName('behavior_plugins[style][settings][groups][]');
     $edit = [
       'behavior_plugins[style][enabled]' => TRUE,
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group'],
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group'],
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
-
-    $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
-
     // Check that the style without a style group is no longer available.
     $this->drupalGet('node/add/paragraphed_test');
-    $this->drupalPostAjaxForm(NULL, [], 'paragraphs_test_style_plugin_add_more');
-    $this->assertText('Style');
-    $this->assertField('paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]');
-    $options = $this->xpath('//select[@name=:name]//option[normalize-space(text())=:text]', [
-      ':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]',
-      ':text' => 'Groupless',
-    ]);
-    $this->assertTrue(!isset($options[0]), 'Groupless style not available.');
-
     // Since Italic Group defines only two styles, assert that only they appear.
     $styles = $this->xpath('//select[contains(@id, :id)]', [':id' => 'edit-paragraphs-0-behavior-plugins-style-style']);
     $this->assertEqual(3, count($styles[0]->option));
@@ -114,11 +96,11 @@
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $this->assertFieldByName('behavior_plugins[style][settings][defaults][italic_test_group]');
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Regular Test Group'],
+      'behavior_plugins[style][settings][groups][]' => ['regular_test_group'],
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => 'Regular Test Group',
+      'behavior_plugins[style][settings][groups][]' => ['regular_test_group'],
       'behavior_plugins[style][settings][defaults][regular_test_group]' => 'regular',
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
@@ -207,8 +189,8 @@
 
     // Configure style bold as default.
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => [],
-      'behavior_plugins[style][settings][default]' => 'bold',
+      'behavior_plugins[style][settings][groups][]' => ['bold_test_group'],
+      'behavior_plugins[style][settings][groups_defaults][bold_test_group][default]' => 'bold',
     ];
     $this->drupalPostForm('admin/structure/paragraphs_type/' . $paragraph->getType(), $edit, t('Save'));
 
@@ -273,7 +255,6 @@
     // Assert global settings.
     $this->drupalGet('admin/reports/paragraphs_collection/styles');
     $this->assertFieldByName('styles[bold][enabled]', FALSE);
-    $this->assertFieldByName('styles[groupless][enabled]', FALSE);
     $this->assertFieldByName('styles[italic][enabled]', FALSE);
     $this->assertFieldByName('styles[regular][enabled]', FALSE);
     $this->assertFieldByName('styles[underline][enabled]', FALSE);
@@ -293,7 +274,6 @@
     // Update global settings and enable two styles.
     $this->drupalGet('admin/reports/paragraphs_collection/styles');
     $edit = [
-      'styles[groupless][enabled]' => TRUE,
       'styles[italic][enabled]' => TRUE,
     ];
     $this->drupalPostForm(NULL, $edit, 'Save configuration');
@@ -306,8 +286,7 @@
     $options = $this->xpath('//*[contains(@class,"paragraphs-style")]/option');
     $this->assertEqual(3, count($options));
     $this->assertEqual($options[0], '- Default -');
-    $this->assertEqual($options[1], 'Groupless');
-    $this->assertEqual($options[2], 'Italic');
+    $this->assertEqual($options[1], 'Italic');
 
     // Check that styles are not shown in style config when disabled.
     $edit = [
@@ -344,13 +323,14 @@
     // Restrict the paragraphs type to the "Italic Test Group" style group.
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group'],
+      'behavior_plugins[style][enabled]' => TRUE,
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group'],
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
     $edit = [
       'behavior_plugins[style][enabled]' => TRUE,
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group'],
-      'behavior_plugins[style][settings][defaults][italic_test_group]' => 'italic',
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group'],
+      'behavior_plugins[style][settings][groups_defaults][italic_test_group][default]' => 'italic',
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     // Create a paragraphed test node and check the style classes.
@@ -371,23 +351,23 @@
     // Configure two groups and set their defaults.
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group', 'Regular Test Group'],
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group', 'regular_test_group'],
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group', 'Regular Test Group'],
-      'behavior_plugins[style][settings][defaults][regular_test_group]' => 'regular',
-      'behavior_plugins[style][settings][defaults][italic_test_group]' => 'italic',
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group', 'regular_test_group'],
+      'behavior_plugins[style][settings][groups_defaults][regular_test_group][default]' => 'regular',
+      'behavior_plugins[style][settings][groups_defaults][italic_test_group][default]' => 'italic',
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     // Check the selects elements for each enabled group and check the classes.
     $node = $this->getNodeByTitle('title_to_remember');
     $this->drupalGet('node/' . $node->id() . '/edit');
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][regular_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][regular_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Regular -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][italic_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Italic -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
@@ -398,21 +378,21 @@
     // Configure Regular as a default style.
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Regular Test Group'],
+      'behavior_plugins[style][settings][groups][]' => ['regular_test_group'],
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Regular Test Group'],
-      'behavior_plugins[style][settings][defaults][regular_test_group]' => 'bold',
+      'behavior_plugins[style][settings][groups][]' => ['regular_test_group'],
+      'behavior_plugins[style][settings][groups_defaults][regular_test_group][default]' => 'bold',
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     // Check that there is only one select and only one style class.
     $this->drupalGet('node/' . $node->id() . '/edit');
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][regular_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][regular_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Bold -', $styles[0]->option[0]);
     $this->assertEqual('Regular', $styles[0]->option[1]);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][italic_test_group]']);
     $this->assertEqual([], $styles);
     $this->drupalGet('node/' . $node->id());
     $this->assertNoRaw('paragraphs-behavior-style--italic');
@@ -421,27 +401,27 @@
     // Configure Regular as a default style.
     $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group', 'Regular Test Group', 'Underline Test Group'],
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group', 'regular_test_group', 'underline_test_group'],
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
     $edit = [
-      'behavior_plugins[style][settings][groups][]' => ['Italic Test Group', 'Regular Test Group', 'Underline Test Group'],
-      'behavior_plugins[style][settings][defaults][italic_test_group]' => 'italic',
-      'behavior_plugins[style][settings][defaults][regular_test_group]' => 'regular',
-      'behavior_plugins[style][settings][defaults][underline_test_group]' => 'underline',
+      'behavior_plugins[style][settings][groups][]' => ['italic_test_group', 'regular_test_group', 'underline_test_group'],
+      'behavior_plugins[style][settings][groups_defaults][italic_test_group][default]' => 'italic',
+      'behavior_plugins[style][settings][groups_defaults][regular_test_group][default]' => 'regular',
+      'behavior_plugins[style][settings][groups_defaults][underline_test_group][default]' => 'underline',
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     // Check that there is only one select and only one style class.
     $this->drupalGet('node/' . $node->id() . '/edit');
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][regular_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][regular_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Regular -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][italic_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Italic -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][underline_test_group]']);
+    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][styles][underline_test_group]']);
     $this->assertEqual(2, count($styles[0]->option));
     $this->assertEqual('- Underline -', $styles[0]->option[0]);
     $this->assertEqual('Bold', $styles[0]->option[1]);
@@ -453,38 +433,12 @@
     // Change a plugin.
     $this->drupalGet('node/' . $node->id() . '/edit');
     $edit = [
-      'paragraphs[0][behavior_plugins][style][style_wrapper][regular_test_group]' => 'bold'
+      'paragraphs[0][behavior_plugins][style][style_wrapper][styles][regular_test_group]' => 'bold'
     ];
     $this->drupalPostForm(NULL, $edit, 'Save');
     $this->assertRaw('paragraphs-behavior-style--italic');
     $this->assertRaw('paragraphs-behavior-style--bold');
     $this->assertRaw('paragraphs-behavior-style--underline');
-
-    // Configure no groups.
-    $this->drupalGet('admin/structure/paragraphs_type/' . $paragraph_type);
-    $edit = [
-      'behavior_plugins[style][settings][groups][]' => [],
-    ];
-    $this->drupalPostAjaxForm(NULL, $edit, 'behavior_plugins[style][settings][groups][]');
-    $edit = [
-      'behavior_plugins[style][settings][groups][]' => [],
-    ];
-    $this->drupalPostForm(NULL, $edit, t('Save'));
-    // Check that there is only one select and only one style class.
-    $this->drupalGet('node/' . $node->id() . '/edit');
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][regular_test_group]']);
-    $this->assertEqual([], $styles);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][italic_test_group]']);
-    $this->assertEqual([], $styles);
-    $styles = $this->xpath('//select[contains(@name, :name)]', [':name' => 'paragraphs[0][behavior_plugins][style][style_wrapper][underline_test_group]']);
-    $this->assertEqual([], $styles);
-    $edit = [
-      'paragraphs[0][behavior_plugins][style][style_wrapper][style]' => 'underline'
-    ];
-    $this->drupalPostForm(NULL, $edit, 'Save');
-    $this->assertNoRaw('paragraphs-behavior-style--italic');
-    $this->assertNoRaw('paragraphs-behavior-style--bold');
-    $this->assertRaw('paragraphs-behavior-style--underline');
   }
 
 }
only in patch2:
unchanged:
--- a/modules/paragraphs_collection_demo/paragraphs_collection_demo.paragraphs.style.yml
+++ b/modules/paragraphs_collection_demo/paragraphs_collection_demo.paragraphs.style.yml
@@ -2,27 +2,27 @@ paragraphs-green:
   title: 'Green'
   description: 'Green background with white font color, text centered.'
   groups:
-    - 'General Group'
+    - 'general_group'
   libraries:
     - 'paragraphs_collection_demo/style'
 paragraphs-blue:
   title: 'Blue'
   description: 'Blue background with white font color, text centered.'
   groups:
-    - 'General Group'
+    - 'general_group'
   libraries:
     - 'paragraphs_collection_demo/style'
 paragraphs-slideshow-light:
   title: 'Slideshow Light'
   description: 'Light blue background with centered text.'
   groups:
-    - 'Slideshow Group'
+    - 'slideshow_group'
   libraries:
     - 'paragraphs_collection_demo/style'
 paragraphs-slideshow-dark:
   title: 'Slideshow Dark'
   description: 'Dark blue background with centered text.'
   groups:
-    - 'Slideshow Group'
+    - 'slideshow_group'
   libraries:
     - 'paragraphs_collection_demo/style'
only in patch2:
unchanged:
--- /dev/null
+++ b/modules/paragraphs_collection_demo/paragraphs_collection_demo.paragraphs.style_group.yml
@@ -0,0 +1,4 @@
+general_group:
+  label: 'General Group'
+slideshow_group:
+  label: 'Slideshow Group'
only in patch2:
unchanged:
--- a/modules/paragraphs_collection_test/paragraphs_collection_test.paragraphs.style.yml
+++ b/modules/paragraphs_collection_test/paragraphs_collection_test.paragraphs.style.yml
@@ -2,7 +2,7 @@ regular:
   title: 'Regular'
   description: 'Default style.'
   groups:
-    - 'Regular Test Group'
+    - 'regular_test_group'
   libraries:
     - 'paragraphs_collection_test/style'
   classes:
@@ -13,29 +13,23 @@ bold:
   title: 'Bold'
   description: 'Bold text.'
   groups:
-    - 'Bold Test Group'
-    - 'Italic Test Group'
-    - 'Underline Test Group'
-    - 'Regular Test Group'
+    - 'bold_test_group'
+    - 'italic_test_group'
+    - 'underline_test_group'
+    - 'regular_test_group'
   libraries:
     - 'paragraphs_collection_test/style'
 italic:
   title: 'Italic'
   description: 'Italic text.'
   groups:
-    - 'Italic Test Group'
+    - 'italic_test_group'
   libraries:
     - 'paragraphs_collection_test/style'
 underline:
   title: 'Underline'
   description: 'Underlined text.'
   groups:
-    - 'Underline Test Group'
-  libraries:
-    - 'paragraphs_collection_test/style'
-groupless:
-  title: 'Groupless'
-  description: 'A test style that does not belong to any style groups.'
-  groups: [  ]
+    - 'underline_test_group'
   libraries:
     - 'paragraphs_collection_test/style'
only in patch2:
unchanged:
--- /dev/null
+++ b/modules/paragraphs_collection_test/paragraphs_collection_test.paragraphs.style_group.yml
@@ -0,0 +1,8 @@
+regular_test_group:
+  label: 'Regular Test Group'
+bold_test_group:
+  label: 'Bold Test Group'
+italic_test_group:
+  label: 'Italic Test Group'
+underline_test_group:
+  label: 'Underline Test Group'
only in patch2:
unchanged:
--- a/paragraphs_collection.services.yml
+++ b/paragraphs_collection.services.yml
@@ -2,6 +2,9 @@ services:
   paragraphs_collection.style_discovery:
     class: \Drupal\paragraphs_collection\StyleDiscovery
     arguments: ['@module_handler', '@string_translation', '@controller_resolver', '@cache.discovery', '@theme_handler', '@config.factory']
+  paragraphs_collection.style_group_discovery:
+    class: \Drupal\paragraphs_collection\StyleGroupDiscovery
+    arguments: ['@module_handler', '@cache.discovery', '@theme_handler', '@config.factory', '@paragraphs_collection.style_discovery']
   paragraphs_collection.grid_layout_discovery:
     class: \Drupal\paragraphs_collection\GridLayoutDiscovery
     arguments: ['@module_handler', '@cache.discovery', '@theme_handler']
only in patch2:
unchanged:
--- /dev/null
+++ b/src/StyleGroupDiscovery.php
@@ -0,0 +1,129 @@
+<?php
+
+namespace Drupal\paragraphs_collection;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Discovery\YamlDiscovery;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Provides common helper methods for style group discovery.
+ */
+class StyleGroupDiscovery implements StyleGroupDiscoveryInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * Collection of style groups with their definition.
+   *
+   * @var array
+   */
+  protected $groupCollection;
+
+  /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
+  /**
+   * Collection of styles with its definition.
+   *
+   * @var array
+   */
+  protected $stylesDiscovery;
+
+  /**
+   * The cache backend.
+   *
+   * @var \Drupal\Core\Cache\CacheBackendInterface
+   */
+  protected $cache;
+
+  /**
+   * The theme handler.
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * Contains the configuration object factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Constructs a new YamlStyleDiscovery.
+   *
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   The cache backend.
+   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
+   *   The theme handler.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config
+   *   The configuration factory object.
+   */
+  public function __construct(ModuleHandlerInterface $module_handler, CacheBackendInterface $cache_backend, ThemeHandlerInterface $theme_handler, ConfigFactoryInterface $config, StyleDiscoveryInterface $style_discovery) {
+    $this->moduleHandler = $module_handler;
+    $this->themeHandler = $theme_handler;
+    $this->cache = $cache_backend;
+    $this->configFactory = $config;
+    $this->stylesDiscovery = $style_discovery;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getStyleGroups() {
+    $cache_id = 'paragraphs_collection_style_group';
+    if ($this->groupCollection !== NULL) {
+      return $this->groupCollection;
+    }
+    else if ($cached = $this->cache->get($cache_id)) {
+      $this->groupCollection = $cached->data;
+    }
+    else {
+      $yaml_discovery = $this->getYamlDiscovery();
+      $this->groupCollection = [];
+      foreach ($yaml_discovery->findAll() as $module => $groups) {
+        foreach ($groups as $group => $definition) {
+          if (empty($definition['label'])) {
+            throw new InvalidStyleException('The "label" of "' . $group . '" must be non-empty.');
+          }
+          $this->groupCollection[$group] = $this->t($definition['label']);
+        }
+      }
+      $this->cache->set($cache_id, $this->groupCollection);
+    }
+    return $this->groupCollection;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getGroupLabel($group_id) {
+    $groups = $this->getStyleGroups();
+    if (in_array($group_id, array_keys($groups))) {
+      return $groups[$group_id];
+    }
+    return NULL;
+  }
+
+  /**
+   * Gets the YAML discovery.
+   *
+   * @return \Drupal\Core\Discovery\YamlDiscovery
+   *   The YAML discovery.
+   */
+  protected function getYamlDiscovery() {
+    return new YamlDiscovery('paragraphs.style_group', $this->moduleHandler->getModuleDirectories() + $this->themeHandler->getThemeDirectories());
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/src/StyleGroupDiscoveryInterface.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\paragraphs_collection;
+
+/**
+ * Provides discovery for a YAML style files in specific directories.
+ *
+ * @package Drupal\paragraphs_collection
+ */
+interface StyleGroupDiscoveryInterface {
+
+  /**
+   * Gets style groups.
+   *
+   * @return array
+   *    Collection of style groups.
+   */
+  public function getStyleGroups();
+
+  /**
+   * Gets group label.
+   *
+   * @param string $group_id
+   *   The group id.
+   *
+   * @return string
+   *   The translatable group label.
+   */
+  public function getGroupLabel($group_id);
+
+}