Union is the thirteenth studio album by the English progressive rock band Yes, released on 30 April 1991 by Arista Records. Production began in 1990 following the amalgamation of two bands featuring current and previous members of Yes at the time: Yes, formed of Chris Squire, Trevor Rabin, Tony Kaye, and Alan White; and Anderson Bruford Wakeman Howe (ABWH), formed of Jon Anderson, Steve Howe, Rick Wakeman, and Bill Bruford. The album is a collection of tracks written by each group separately; the eight members do not all play together. Production was met with differences from the beginning, including the merger of ABWH and Yes, the group's internal relations, and Anderson and producer Jonathan Elias's decision to have session musicians play parts already put down by Wakeman and Howe.