The Beastie boys is an American Band that plays Hip Hop, it was formed in 1981
I love the Beastie Boys! I remember them well. I cannot remember how many were in the band, do you know?
They were 3, Micheal Diamond,Adam Yach, and Adam Horovitz 
What was their #1 hit?
Their first EP as they call it was first EP, called  "Polly Wog Stew" was released in 1982.
I think my favorite song from them was "Fight for your Right to Party". Any idea what year that came out?
(drums). They appeared on the compilation cassette "New York Thrash", contributing two songs from their first EP, "Polly Wog Stew", in 1982. Berry left shortly thereafter and was replaced by Horovitz. After achieving local success with the 1983 experimental hip hop single "Cooky Puss", the Beastie Boys made a full transition to hip hop, and Schellenbach left the group soon after. They toured with Madonna in 1985 and a year later released their debut album "Licensed to Ill". It was
Beastie Boys
The Beastie Boys were an American hip hop group from New York City formed in 1981. The group comprised Michael "Mike D" Diamond (vocals, drums), Adam "MCA" Yauch (vocals, bass) and Adam "Ad-Rock" Horovitz (vocals, guitar).
The Beastie Boys were formed as a four-piece hardcore punk band, the Young Aborigines, in 1979 by Mike D (vocals), MCA (bass), John Berry (guitar) and Kate Schellenbach