[6] While Mansfield in 1978 was working on the album, The Statue Makers of Hollywood with The Alpha Band, he appeared as a guitarist on Desire Wire by a struggling pop/rock artist Cindy Bullens that same year.
[7] In 1986, Mansfield was an initial member of Bruce Hornsby and the Range,[8] including playing the title instrument on the hit "Mandolin Rain".
Since The Alpha Band broke up, Mansfield has continued to work as a musician in sessions for Dylan, Burnett, Johnny Cash, Nanci Griffith, Roger McGuinn, Sam Phillips, Mark Heard, The Roches, Edie Brickell, Spinal Tap, Lucinda Williams, Dwight Yoakam, Victoria Williams, Loudon Wainwright III, Willie Nile, Chris Hillman and Herb Pedersen and others.
Mansfield composed the music for the 1980 film Heaven's Gate – he appeared in the movie, playing the fiddle on roller skates – and has since gone on to write scores for a number of other films, including others directed by Heaven's Gate's Michael Cimino.
[10] He also composed the music for the soundtrack to The Ballad of Little Jo (1993), a movie written and directed by Maggie Greenwald, whom he married in 1994.