The Modern Jazz Quartet (MJQ) was an influential music group established in 1952 and for most of their long career composed of John Lewis (piano, musical director), Milt Jackson (vibraphone), Percy Heath (double bass), and Connie Kay (drums). Initially active into the 1970s until Jackson quit due to creative disagreement and frustration with their busy touring schedule, the MJQ reformed intermittently into the 1990s.