One of my favorite bands, the Beastie Boys, were a group from New York City formed in 1981.
I know a couple of their songs, but not many.  What was their first big hit?
I'm not sure about their first big song -- but their debut album "Licensed to Ill" was released after a tour with Madonna in 1985.
I didn't know they had been around that long.  How many members are there?
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
Hold It Now, Hit It
"Hold It Now, Hit It" is a song by American hip hop group Beastie Boys, released as the first 
single from their debut album "Licensed to Ill". It is also remixed on the album "New York State of Mind".
In 2008, it was ranked number 27 on VH1's 100 Greatest Songs of Hip Hop. 
Samples and use in sampling.
The song contains samples from "The Return of Leroy" by The Jimmy Castor Bunch