A language pack is a Firefox extension that changes the language that is displayed in the Firefox application. When you change the language pack, all menus, optionspreferences, and text that is part of the Firefox application is displayed in the language of the downloaded language pack.

Note: A language pack does not affect the language of web content that you download. Nor does it change the language of Firefox's built-in spell-checker. To change the spell-check language, you must download a dictionary. For more information, see Using the spell checker.

For example, the following image displays Firefox using an American English language pack:

If you download and install a Greek language pack, the same image looks like the following:

Installing a new language pack

If you do not plan on switching back and forth between languages, it is better to re-install Firefox in the language you prefer from the Firefox downloads page.

1. Go to the Mozilla FTP site.
2. Select the version of Firefox you are using.
   • You can find your Firefox version number by selecting the HelpFirefox menu from the menu bar, and then selecting About Mozilla Firefox.
3. Select the win32maclinux-i686 folder.
4. Select the xpi folder.
5. Select the .XPI file for the desired language pack. For some languages, there are multiple regional packs. For example, the Greek language pack is el.xpi.
   • After you select the language pack to download, if a yellow bar appears at the top of the main Firefox window, your download settings are preventing you from downloading the language pack. Click Edit Options.... In the Allowed Sites - Add-ons Installations dialog, click Allow. Then, click Close, and click the .XPI file again.
6. Click Install Now.
7. To complete installation of the language pack, you must restart Firefox. Click Restart Firefox.

• To see a list of all installed language packs, in the menu at the top of the Firefox window, select the Tools menu and then select Add-ons. Click the Languages tab.

Using the Language Pack

After you have installed the language pack, you must enable it from within Firefox through a preference.

1. In the Location bar, type about:config, and press EnterReturn.
   • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page.
2. In the list of preferences, enter general.useragent.locale in the Filter textbox.
3. There should be only one preference displayed. Double-click it.
4. Enter the value for the language pack to use. This value should be the .XPI filename without the ".XPI" extension. In our example above, the value to enter for the Greek language pack is: el.
   • If you switch language packs often, you may want to download an extension such as Locale Switcher to help.
5. To apply the changes throughout Firefox, you must restart Firefox.

Based on information from Language packs (mozillaZine KB)