function GetUILanguage: Integer;
Returns the language identifier (LANGID) of the current user's UI language, which is either the language of Windows itself, or in the case of a MUI edition of Windows, the user interface language chosen in Control Panel's Regional Options. Returns 0 if the function fails (unlikely).
Refer to the list of valid language identifiers on MSDN.
begin if GetUILanguage = $0409 then begin // UI language is English (United States) end; // You can use "and $3FF" to extract the primary language identifier if GetUILanguage and $3FF = $09 then begin // Matches any variant of English end; end;