The Jazz Composer's Orchestra was an American jazz group founded by Carla Bley and Michael Mantler in 1965 to perform orchestral avant-garde jazz. Its origins lay in the Jazz Composers Guild, an organization founded by Bill Dixon which grew out of the series of 1964 concerts in New York, known as the "October Revolution in Jazz" and subsequent regular performance settings. A big band, formed by Bley and Mantler, became known as the Jazz Composers Guild Orchestra, which made its first record in April 1965. After the demise of the Guild, the big band continued as the Jazz Composer's Orchestra. A non-profit organisation was established in 1966, the Jazz Composers Orchestra Association Inc. (JCOA).