Do you see that language under Tools > Add-ons > Languages?

You need to change the general.useragent.locale pref to sv-SE to make Firefox use this language pack.

• http://kb.mozillazine.org/about:config

Close and restart Firefox after changing the pref.

• Locale Switcher: https://addons.mozilla.org/firefox/addon/locale-switcher/
• Quick Locale Switcher: https://addons.mozilla.org/firefox/addon/quick-locale-switcher/

You can install the Swedish language pack (sv-SE.xpi) from one of these pages it the add-ons site doesn't work.

• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/20.0.1/win32/xpi/
• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/20.0/win32/xpi/

Sorry, it didn't work. What changed was

• Firefox is now in Swedish (not an improvement!)
• Swedish is now the only item in Tools/Add-ons/Languages

... but the spell check only has British and US English.

A language pack is supposed to change the language as sen in the user interface.

You need to install the Swedish spell checking dictinary if you want to do spell checking in Swedish

• http://extensions.openoffice.org/project/aoo-dict-sv

Open the oxt (ZIP) archive with a suitable archive manager (you may need to rename the file to .zip) and copy the files xx-XX.aff and xx-XX.dic to the clipboard (right-click: Copy).

Go to the Firefox program folder C:\Program Files\Mozilla Firefox and then to the dictionaries folder and paste the two files xx-XX.aff and xx-XX.dic in the dictionaries folder.

• http://kb.mozillazine.org/Dictionaries#Installing_manually_to_the_application

There is a sv-SE.aff but no sv-SE.dic in the unzipped folder. There is a sv-SE file with no file extension, it looks like a txt file. Is that the .dic file? Should I rename it first?

Also, the reason why I asked the first question was because when I try to spell check I get a pop-up menu where "Spell check" is an option and below that, "Languages" and there, "Add dictionary" which takes me to https://addons.mozilla.org/sv-SE/firefox/language-tools/, and when I choose the Swedish language pack there I get https://addons.mozilla.org/sv-SE/firefox/addon/svenska-se-language-pack/ and then I download it (hoping that all the people that have left bad reviews are wrong) and then it doesn't work. And then I came here :)

There is a sv_SE.aff and a sv_SE.dic in that archive.
If you do not see the file extension of the latter then Windows may be hiding it.
Try to extract the two files and check the file type via the Properties in the right-click context menu.

It worked! I'm so glad, thank you.

If you are just looking for a Swedish dictionary (SV: svensk ordlista) a version can be found in Mozilla's FTP server as the file: svensk_ordlista-1.49-tb+sm+fx.xpi

How to: Swedish Dictionary in Mozilla Thunderbird and Firefox