[2] The first three had worked together as members of the Black Artists' Group in St. Louis, Missouri, and had appeared together on Anthony Braxton's album New York, Fall 1974.

[3] In 1991, Hemphill left the group due to illness, and was replaced by Arthur Blythe,[2] although several saxophonists have filled his chair in the years since.

[4] Beginning in the early 1980s, the quartet used Bluiett's composition "Hattie Wall" (released on W.S.Q., Live in Zurich, Dances and Ballads, Steppenwolf and Yes We Can) as a signature theme for the group.

[5] The group principally recorded and performed as a saxophone quartet, usually with a line-up of two altos, tenor, and baritone (reflecting the composition of a classical string quartet), but were also joined later in their career by drummers, bassists, and other musicians.

These guests have included Sam Rivers, Tony Kofi, Steve Potts, Branford Marsalis, James Spaulding and Jorge Sylvester.