(written from a Production point of view)
The Yellowjackets are an American jazz fusion quartet which arranged and performed two original tracks heard on the soundtrack for Star Trek IV: The Voyage Home.
Originally founded as the Robben Ford Group in 1977, the band became The Yellowjackets in 1981. At the time The Yellowjackets contributed to Star Trek IV's soundtrack, the group was comprised of keyboardist Russell Ferrante, electric bassist Jimmy Haslip, saxophonist Marc Russo, and drummer Ricky Lawson.
The two compositions the group contributed for Star Trek IV were "Market Street" (which can be heard in the film as Kirk and company are first seen walking the streets of 20th century San Francisco) and "Ballad of the Whale". The latter track, which re-arranged a piece from Leonard Rosenman's film score, was not used in the film although it was included on the soundtrack album.  Quartet members Ferrante and Haslip worked with Rosenman to compose both tracks.
The Yellowjackets have released 19 albums and 3 compilation sets since 1981. Their latest album, Twenty Five, was released in 2006 as celebration of the band's twenty-fifth anniversary. They have been part of the Heads Up record label since 1995, having previously been signed with Warner Bros. Records and MCA Records.