kojitanaka, Both 'got' and 'gotten' are acceptable past participles in American English, but there is a difference. It is not simply an alternative for have 'got'. Gotten is used in such contexts as They've gotten a new boat. (= obtain) They've gotten interested. (= become) He's gotten off the chair. (= moved) But it is not used in the sense of possession. I've got a car = I have a car. We use 'got' for possession in the same sense as the British do. I've gotten a car. = I've obtained a car. The availability of gotten allows American to differentiate between. My son has got to play. = My son must play. My son has gotten to play. = My son was able to play. And yes, I have used it quite often in my lifetime. I have lived in Southern Canada and the Northern Midwest, mostly in Michigan...and it is grammtically correct. :)

Not an answer really, but just wanted to comment. I am....ahem ... at the upper range of your age group and have never used "gotten" in my life. As a college graduate, and someone who also considers himself fairly well-read, I can't really recall ever coming across that word at anytime as well. It is part of the language, but its usage no longer seem popular since they are other/better/easier ways to express what you are trying to say. If you're interested, the below links explain it better than I ever could try to! Thanks for sharing your question (one which definitely made me think!). www-personal.umich.edu/~jlawler/aue/gotten.html grammar.quickanddirtytips.com/is-got-proper-english.asp...

I forget. BTW， “gotten" always means "became". You can never say: "I have gotten a car."That is plain wrong. You CAN say: "I have gotten rich." That is fine.

"got", "gotten" is never proper English, although "I have gotten rich" is acceptable in daily speech. The proper way is always, "I became rich". Like in Japanese, you never call your boss "chan", "kun" but "san", perhaps "sama" or even "dono same"; Instead of watashi, you say atashi. Proper usage to whom you are talking to. That's all. Teenage talk can never be trusted at all. There was a time when the rage was "Valley talk" by California teenage girls. Valley talk is now considered passe by the younger generations of today.

Maybe in some contexts like he has gotten richer, though I think in informal speech, people just tend to use got...