While a graduate student at the University of North Texas College of Music, Summerlin, in 1959, composed Requiem for Mary Jo, which is widely believed to be one of the first significant uses of jazz in a liturgical service.
He performed Requiem for Mary Jo May 20, 1959, during a service in the chapel at the Perkins School of Theology, Southern Methodist University.
[3] That same year, still studying and teaching at North Texas, Summerlin recorded his debut LP, Liturgical Jazz, on which "Requiem for Mary Jo," was the heartbreaking centerpiece.
[14] Summerlin relocated to New York in the early 1960s, where he freelanced with Eric Dolphy, Pete LaRoca, Don Ellis, and Sheila Jordan.
He also composed and arranged for Ron Carter, Kuhn, Freddie Hubbard, Dave Liebman, Toshiko Akiyoshi, and Lee Konitz.