https://support.mozilla.org/en-US/kb/how-do-i-use-firefox-spell-checker ''<p>gamecare76 [[#question-1574830|said]]</p>'' <blockquote>I have installed the English GB language for spellchecking, but it doesnt show in the dropdown menu. It only shows Dutch. </blockquote> It sounds like you installed the English (GB) Language Pack and not a en-GB Dictionary. Your own screenshot even gives you an essential clue on what you need for the spell checker when it says "Add Dictionaries". Language Packs are used as a way to have one Firefox install but be able to switch between two or more languages that changes the menus and settings language such in Firefox. On top of https://addons.mozilla.org/firefox/language-tools/ in English it says. <blockquote>Installing a dictionary add-on will add a new language option to your spell-checker, which checks your spelling as you type in Firefox. Language packs change your browser’s interface language, including menu options and settings.</blockquote> There are three British English '''dictionaries''' in the right column though one is incorrectly referred to as a spellchecker when the inline spell checker is built in Firefox.