diff --git a/docs/setup.rst b/docs/setup.rst
--- a/docs/setup.rst
+++ b/docs/setup.rst
@@ -67,6 +67,21 @@ You are now ready to use Kallithea. To r
   repositories.
 
 
+Internationalization (i18n support)
+-----------------------------------
+The Kallithea web interface is automatically displayed in the user's preferred
+language, as indicated by the browser. Thus, different users may see the
+application in different languages. If the requested language is not available
+(because the translation file for that language does not yet exist or is
+incomplete), the language specified in setting ``i18n.lang`` in the Kallithea
+configuration file is used as fallback. If no fallback language is explicitly
+specified, English is used.
+
+If you want to disable automatic language detection and instead configure a
+fixed language regardless of user preference, set ``i18n.enabled = false`` and
+set ``i18n.lang`` to the desired language (or leave empty for English).
+
+
 Using Kallithea with SSH
 ------------------------