Influential figure in the 1960s free-jazz movement and innovative trio player. He was known for his melodic voicing and use of space.
He and Sonny Rollins toured and recorded together, eventually producing an album in collaboration with Coleman Hawkins titled Sonny Meets Hawk! in 1963.
He helped found the Jazz Composers Guild in 1964, dedicated to uniting New York free jazz artists, including his ex-wife Carla Bley. The Guild became one of the forces behind the jazz revolution in 1964.
He was the conductor for Charle Mingus' album Charles Mingus and His Orchestra from 1953.