He studied at Westmont College, graduating in 1976, then took his MA in composition at California State University.
His sextet, active from 1982 to 1985, included Golia, Wayne Peet, Alex Cline, and Roberto Miguel Miranda; his octet, active from 1985 to 1990, had Golia, Cline, Ken Filiano, John Fumo, Kim Richmond or Steve Fowler, and Bill Roper as members.
Rapson moved to the East Coast in 1990, studying at Wesleyan University, where he pursued his doctorate in ethnomusicology.
[2] He played with Anthony Braxton in 1992 and worked with Ed Blackwell (1990–1991), Jay Hoggard (1990–1992), and Allen Lowe (1991–1992).
He led his own big band in 1994, the OftENsemble, and formed the Oddball Trio Plus Trombone in 1996 with Steve Grismore.