How long does it take to get proficient in Chinese?

An article in today's New York Times seems to have some anecdotal evidence that you can get proficient in Chinese—despite working full time and using some degree of English at work—in about two years.

“I didn’t know anything about China,” said [Joshua Arjuna Stephens, who graduated from Wesleyan University in 2007 with a bachelor’s degree in American studies]. “People thought I was nuts to go not speaking the language, but I wanted to do something off the beaten track.”

Two years later, after stints in the nonprofit sector and at a large public relations firm in Beijing, he is highly proficient in Mandarin . . .

After two years of living and working in China, [Sarabeth Berman, a 2006 graduate of Barnard College with a major in urban studies,] is proficient in Mandarin.

So there you have it: two years.

Links: American Graduates Finding Jobs in China [New York TImes]