Interested in learning two languages together, or learning a third language through your second?
Although the majority of courses at Duolingo in other languages are for learning English, there are some courses designed for native speakers of other languages to learn languages such as French, Spanish, German, etc. If you’re already used to the interface in English, it is quite easy to change to another language and try the courses available.
And of course, if you already speak another language, you can always use that language to learn another. Depending on how closely related the languages are, it may be easier to learn a third language through your second language instead of your native language. Personally, I prefer to learn Spanish through French rather than English.
As of mid 2016, the following languages offer Duolingo courses in more than just English:
For Spanish speakers – English, French, Portuguese, Italian, German and Catalan, while Guarani and Esperanto are almost ready

Duolingo courses currently available for Spanish speakers
For French speakers – English, Spanish, Italian, German, and Portuguese
For Italian speakers – English, French, German, and Spanish
For Portuguese speakers – English, Spanish, French, German, and Italian
For German speakers – English, French, and Spanish
For Russian speakers – English, German, French, Spanish, and Swedish
For Arabic speakers – English, French, German, and Swedish
For Turkish speakers – English, German, Russian, and French
For Chinese speakers – English, Spanish, and French
For reference, English speakers can currently learn the following languages on Duolingo: Spanish, French, German, Italian, Portuguese, Dutch, Swedish, Irish, Russian, Turkish, Danish, Norwegian (Bokmål), Esperanto, Ukrainian, Polish, Welsh, and Vietnamese. Hungarian, Greek, Hebrew, Czech, and Romanian will be released next, with Swahili, Hindi, Klingon, Korean, Indonesian, and Yiddish to follow (but not for a while!)
Don’t forget that you can learn two languages together, or multiple languages simultaneously, with our multilingual comparative resources.
Dr. Wagner has a PhD in Linguistics and is dedicated to learning and teaching languages online and abroad. She has studied in Quebec and Australia, taught English in France, and is currently based in the US.