Anatomically you are designed to learn an unlimited number of languages,but where is the will? If you have it ,time and effort will limit your ability. However as you see from the above posts that some people have managed to learn quite a large number of languages, that is many times due to similarity of structure and vocabulalry between languages of the same family.

I can speak 3 languages and I hope to learn more ;o) hehehe thanks to friend from italki I know some words in Chinese and Russian and others. If I had got time I would have learned many languages. So I would check myself how many languages I can learn.

This is some famous examples who have gone through times... Very impressive : http://how-to-learn-any-language.com/forum/forum_posts.asp?TID=297&PN=12 http://en.wikipedia.org/wiki/Giuseppe_Caspar_Mezzofanti http://en.wikipedia.org/wiki/Kenneth_L._Hale http://en.wikipedia.org/wiki/Stephen_Wurm http://en.wikipedia.org/wiki/Ziad_Fazah Source : http://fr.answers.yahoo.com/question/index?qid=20100627151621AArWWji

The person can SPEAK only ONE language! (at once). But, in which language he speaks, that is other problem!

I think pepole's abilities to master languages are limited.in my opinion,3 are enough!