[5] Avant-garde jazz originated in the mid- to late 1950s among a group of improvisors who rejected the conventions of bebop and post bop in an effort to blur the division between the written and the spontaneous.
Ornette Coleman and Cecil Taylor led the way, soon to be joined by John Coltrane.
Some would come to apply it differently from free jazz, emphasizing structure and organization by the use of composed melodies, shifting but nevertheless predetermined meters and tonalities, and distinctions between soloists and accompaniment.
[6] In Chicago, the Association for the Advancement of Creative Musicians began pursuing their own variety of avant-garde jazz.
The AACM musicians (Muhal Richard Abrams, Anthony Braxton, Roscoe Mitchell, Hamid Drake, and the Art Ensemble of Chicago) tended towards eclecticism.