Steve's musical experiences began at age twelve when he played in Pennsbury (Pennsylvania) High School's progressive music program. By age fourteen he was being hired to play at the local beer hall for eight or ten dollars a night. A few years later he expanded his playing to area symphony orchestras and local big bands. Living close to Philadelphia enabled him to hear such fine players as John Coltrane, Max Roach, Sonny Rollins and Wynton Kelly, integrating what he was hearing into his own music. After high school, Gilmore spent a short time in Toronto attending the Advanced School of Contemporary Music, then staffed by The Oscar Peterson Trio. Ray Brown was his teacher. Upon his return to Pennsylvania in 1961, Steve worked the Pocono Mountains resorts, developing by playing regularly, and with, some very fine musicians including Bob Newman, Jerry Dodgion, Ray Bryant and Jerry Segal.
In 1967, Steve left the Poconos for Miami, Florida without any real plans and stayed for four years, working with jazz great Ira Sullivan and other fine jazz artists including Joe Diorio, Chuck Marohnic, Flip Phillips, Paul Winter and Vince Lawrence. Another move back to the Poconos in 1971 associated him with drummer Bill Goodwin for the first time, and together they formed the rhythm team for several bands including The Chamber Jazz Quintet, Al Cohn and Zoot Sims, Tom Waits, Mose Allison and The National Jazz Ensemble (under the direction of Chuck Israels). In February, 1974 Gilmore and Goodwin both joined The Phil Woods Quartet at it's inception and anchor the Quintet to this day.