diff --git a/django_select2/conf.py b/django_select2/conf.py
index 4d686005..8862932a 100644
--- a/django_select2/conf.py
+++ b/django_select2/conf.py
@@ -87,6 +87,14 @@ class Select2Conf(AppConf):
 
         SELECT2_CSS = 'assets/css/select2.css'
 
+    If you want to add more css (usually used in select2 themes), add a line
+    in settings.py like this::
+
+        SELECT2_CSS = [
+            'assets/css/select2.css',
+            'assets/css/select2-theme.css',
+        ]
+
     If you provide your own CSS and would not like Django-Select2 to load any, change
     this setting to a blank string like so::
 
@@ -96,6 +104,14 @@ class Select2Conf(AppConf):
         develop without an Internet connection.
     """
 
+    THEME = "default"
+    """
+    Select2 supports custom themes using the theme option so you can style Select2
+    to match the rest of your application.
+
+    .. tip:: When using other themes, you may need use select2 css and theme css.
+    """
+
     I18N_PATH = (
         "https://cdnjs.cloudflare.com/ajax/libs/select2/{version}/js/i18n".format(
             version=LIB_VERSION
diff --git a/django_select2/forms.py b/django_select2/forms.py
index 86ca0390..b40b6207 100644
--- a/django_select2/forms.py
+++ b/django_select2/forms.py
@@ -90,6 +90,7 @@ def build_attrs(self, base_attrs, extra_attrs=None):
         default_attrs = {
             "lang": self.i18n_name,
             "data-minimum-input-length": 0,
+            "data-theme": settings.SELECT2_THEME,
         }
         if self.is_required:
             default_attrs["data-allow-clear"] = "false"
@@ -120,18 +121,19 @@ def media(self):
         .. Note:: For more information visit
             https://docs.djangoproject.com/en/stable/topics/forms/media/#media-as-a-dynamic-property
         """
-        select2_js = (settings.SELECT2_JS,) if settings.SELECT2_JS else ()
-        select2_css = (settings.SELECT2_CSS,) if settings.SELECT2_CSS else ()
+        select2_js = [settings.SELECT2_JS] if settings.SELECT2_JS else []
+        select2_css = settings.SELECT2_CSS if settings.SELECT2_CSS else []
 
-        i18n_file = ()
+        if isinstance(select2_css, str):
+            select2_css = [select2_css]
+
+        i18n_file = []
         if self.i18n_name in settings.SELECT2_I18N_AVAILABLE_LANGUAGES:
-            i18n_file = (
-                ("%s/%s.js" % (settings.SELECT2_I18N_PATH, self.i18n_name),)
-            )
+            i18n_file = [f"{settings.SELECT2_I18N_PATH}/{self.i18n_name}.js"]
 
         return forms.Media(
-            js=select2_js + i18n_file + ("django_select2/django_select2.js",),
-            css={"screen": select2_css + ("django_select2/django_select2.css",)},
+            js=select2_js + i18n_file + ["django_select2/django_select2.js"],
+            css={"screen": select2_css + ["django_select2/django_select2.css"]},
         )
 
 
diff --git a/tests/test_forms.py b/tests/test_forms.py
index af988845..5a89dfd1 100644
--- a/tests/test_forms.py
+++ b/tests/test_forms.py
@@ -169,6 +169,11 @@ def test_i18n(self):
             "django_select2/django_select2.js",
         )
 
+    def test_theme_setting(self, settings):
+        settings.SELECT2_THEME = "classic"
+        widget = self.widget_cls()
+        assert 'data-theme="classic"' in widget.render("name", None)
+
 
 class TestSelect2MixinSettings:
     def test_default_media(self):
@@ -209,6 +214,13 @@ def test_empty_css_setting(self, settings):
         result = sut.media.render()
         assert "/select2.css" not in result
 
+    def test_multiple_css_setting(self, settings):
+        settings.SELECT2_CSS = ["select2.css", "select2-theme.css"]
+        sut = Select2Widget()
+        result = sut.media.render()
+        assert "select2.css" in result
+        assert "select2-theme.css" in result
+
 
 class TestHeavySelect2Mixin(TestSelect2Mixin):
     url = reverse("heavy_select2_widget")
@@ -321,6 +333,11 @@ class NoPickle:
         with pytest.raises(NotImplementedError):
             widget.set_to_cache()
 
+    def test_theme_setting(self, settings):
+        settings.SELECT2_THEME = "classic"
+        widget = self.widget_cls(data_view="heavy_data_1")
+        assert 'data-theme="classic"' in widget.render("name", None)
+
 
 class TestModelSelect2Mixin(TestHeavySelect2Mixin):
     form = forms.AlbumModelSelect2WidgetForm(initial={"primary_genre": 1})