The trio started as primarily a jazz unit and released their first album, Ramsey Lewis and the Gentlemen of Swing, in 1956. Following their 1965 hit "The In Crowd" (the single reached No. 5 on the pop charts, and the album No. 2) they concentrated more on pop material. Young and Holt left in 1966 to form Young-Holt Unlimited and were replaced by Cleveland Eaton and Maurice White. White left to form Earth, Wind & Fire and was replaced by Morris Jennings in 1970. Later, Frankie Donaldson and Bill Dickens replaced Jennings and Eaton; Felton Crews also appeared on many 1980's releases.
By 1966, Lewis was one of the nation’s most successful jazz pianists, topping the charts with "The In Crowd", "Hang On Sloopy", and "Wade in the Water". All three singles each sold over one million copies, and were awarded gold discs. Many of his recordings attracted a large non-jazz audience. In the 1970s, Lewis often played electric piano, although by later in the decade he was sticking to acoustic and using an additional keyboardist in his groups. Wikipedia
