When you boot up your Mac for the first time, you see a message where you can select your language. But you can always change the language of OS X. You can select different language options for each user, or set a master language for all accounts and the login screen. Profile only 1. Go to System Preferences and choose International. 2. Drag the languages in the order you want them to be used. The language you set at the top will be used. If there's a program that doesn't support that language, it uses the one that is put below the top one. Now log off and back on to apply the changes to the current user profile. Set master language for all accounts and login screen 1. Open the Terminal, and enter the following command: Code: sudo "/System/Library/CoreServices/Language Chooser.app/Contents/MacOS/Language Chooser" 2. Enter the root password. 3. Finally choose the language from the list.