This was originally a 1974 LP album on Paul Bley's Improvising Artists Label. It is notable for being the first professional recording showcasing the talents of Jaco Pastorius and Pat Metheny. The two had gotten to know each other in Miami the year before. Their collaboration continued on Metheny's debut Bright Size Life together with Bob Moses, recorded in December 1975. The record was released the following year by ECM, also home to Bley since his Open, to Love from 1972.
Although the original title was Pastorius/Metheny/Ditmas/Bley, it soon became known by the unofficial title of Jac.