What is the shortest amount of time that a person could be come fluent in another language? Let’s assume that this person knows a few words in the language but nothing more.
10 years, if you are over the age of 12, past the “critical period” of brain development for language. If you live there, then less time.
This is like asking how much does an animal weigh, your results may vary. 
Even given total immersion, I would think it takes a couple years at minimum. That’s my guess.
I disagree. I think a person could become fluent in a matter of months with total, all encompassing immersion.
I suspect that Esperanto would take only a matter of months to become fluent, asuming pretty regular practice.
I studied it once a week with friends just after HS, and we could converse after a couple of months, and read “On The Beach” in translation shortly after.
11 years of no practice, and a couple of those learning construction site Spanish have trashed most of my competancy in that language.
Martin
How much does a car cost?
Seriously, immersion and study help, but it depends on you age, your absorbtion factor and your desire to learn.
I’ve learned a good deal of espanol from cable TV with minimal exposure (SABADO GIGANTO!)
Good luck, but ‘fluent’ is going to take some serious time and effort.
In How to Learn Languages and What Languages to Learn, the linguist Mario Pei wrote that an English speaker can become become fluent in a relatively easy language (like Spanish or French) in about 6 months, a moderately difficult language (like Russian) in 9 months, and a difficult language (like Chinese) in a year. This supposes you spend virtually every waking hour immersed in that language: reading newspapers and books only in that language, watching television and films only in that language, listening to the radio only in that language, speaking only to native speakers of that language. It’s difficult to immerse yourself to that degree without living in an area where all the people around you speak that language. Even so, many Americans living overseas fall into the trap of speaking only English, to people who speak English as a first or second language.
On the other hand, if you spend only an hour or two a day studying the language, as in language classes offered in most schools, it will take around seven years to become fluent.
It varies all over the board as people have said. It will depend on the language, your effort in learning and your aptitude.
The younger you are, the better. Children just learning to speak can learn two languages (or even 3 in some cases) almost as easily as one.
I recall reading that in order to be functional in most languages, you need a vocabulary of ~10,000 words. How many foreign language words can you learn in a day? 10? 20? Even at 20 per day, it would take a year and a half, while at the same time learning grammar and syntax.
As an interesting side note, I read a few years ago about a guy who is allegedly the world record holder for speaking foreign languages. IIRC, his total was nearly 60 (I would guess that he was more “conversational” than “fluent”). The article claimed that he could learn a new language in the unbelievable time or 2 or 3 months. Now, obviously this guy was a one in a billion (or more) and using him as the measuring stick is like using Mozart as the standard for musical ability. Oddly, I can’t seem to find a site backing this up though.
It also depends how strictly you define “fluent.” Being very good with a language and being fluent in it are very different things.
I am talking about reading, writing and comprehending the language as if you grew up using it as your mother-tongue.
A couple of years ago I spoke with a woman (early twenties) in the train who after half an hour casually mentioned that she was French (we’d been conversing in Dutch, my native tongue), and that she had only started learning the language 3 years ago (living with her BF/husband). Up to that moment I hadn’t noticed at all that she wasn’t originally Dutch. So, assuming she wasn’t lying (and there was no reason why she should) it appears to be possible to learns a new language (*) perfectly within at most several years. Of course she might have been a natural language miracle.
Less concrete evidence from what I’ve seen/heard, living in Europe, where multi-lingual speakers are legion, with a large variety of fluency, I get the impression that obtaining fluency (quickly) after childhood is largely a matter of talent in combination with application. Some people have learned foreign languages in high school and have lived abroad for years but still have atrocious accents, others (I’ve heard from) fit in so well that they start speaking their original language with an accent. I’ve heard stories of people who could master an entirely new language within a matter of months with at least superficial fluency.
Hope this helps the curious.
- For those who are not familiar with the languages: there is hardly any similarity between Dutch and French.
It all depends on how you define fluent. Merriam-Webster defines it as such:
If you only mean the ability to be able to say whatever you want in a language, without going through a conscious translation effort, then I’d say that a few months is enough. (As an anecdotal data point, let me say that I spent two months in a French language class in France. We had 5 hours of classes every day, and I lived in French family. Even though my initial vocabulary consisted (literaly) of ‘oui’, ‘non’ and ‘bonjour’, I only spoke French. After two months I could express anything, without translating, although accent and grammar was rather foreign. That was the fourth language I studied, and it’s right now my third language in fluency.)
If on the other hand, you define fluent as ‘indistinguishable from a native speaker’ (the way jb_007clone and many others here seem to do), I’d say that bibliophage is probably closer to target. It takes a conscious effort over a long time to get the pronounciation right, and even longer to speak idiomaticaly correctly.
If you mean to speak without an accent, it might be impossible except for a small number of talented people. Most people’s brains lose the ability to even hear the sounds in another language after age 12. This has been found with adult native English speakers learning French – no matter how much they hear French, there are certain tones and sounds that they cannot perceive, and cannot learn to speak.
Other examples abound. People move to another country, and live there for 60 years and still have a thick accent. My doctor, from one of the ‘slovakia’ countries took accent lessons to sound like a native English speaker. He can reduce his accent, but he will never be accent-free. Ever known a Scot to lose his accent?
Google terms like “critical period” and language. I think Lenneberg cognitive scientist to address these questions in a major text.
I’m in the several months to a year of intensive study camp. Years ago, I attended the Defense Language Institute in Monterey, CA.
IRRC, at that time, French/Spanish/Italian courses were 6 months, German 8, Russian 12, Chinese, Japanese & Koren 14 or more. The classes were pretty much total immersion for 8 hours a day with non-military native speakers of the language as instructors.
At the end of that training, you were expected to be able to fully understand spoken communication (via radio intercepts) and be able to converse well if needed.
For all but the asian languages, reading and writing was also fairly good at that point. Idiomatic language was harder and emphasized less, but we did master military terms 
As others note, accents are hard to get past - but I later took some French training that used a heavy doses of phonetic training and improved my accent greatly.
… sadly, it is all gone from disuse.
My 1986 Guinness Book (sorry I don’t have a more recent version onhand) has this record:
“The most multilingual living person in the world is Georges Henri Schmidt (b Strasbourg, France, Dec 28, 1914), who served as Chief of the UN Terminology Section 1965-1971. In the 1975 edition of Who’s Who in the United States he listed ‘only’ 19 languages because he was then unable to find the time to ‘revive’ his former fluency in 12 others.”
So I’d say that being fluent in 30+ languages is quite doable, albeit not by many folks, as you pointed out!
Want to become fluent in another language? Join the LDS church and become a missionary. They’ve got a language-immersion program that puts Berlitz to shame!
hm… i would say a few years, but not 10. if you live in that country and have nobody to talk to in your own language maybe 3 - 4 years i think, if you’re bright that is.
i dunno, i came here in 1996, about a year or two ago i actually started using english when conversing with my russian friends