Soul jazz was a development of hard bop which incorporated strong blues and gospel influences in music for small groups featuring keyboards, especially the Hammond organ. Important soul jazz organists include Bill Doggett, Charles Earland, Richard "Groove" Holmes, Les McCann, Brother Jack McDuff, Jimmy McGriff, Donald Patterson, Jimmy Smith and Johnny Hammond Smith. Tenor saxophone was also important in soul jazz; important soul jazz tenors include Gene Ammons, Eddie "Lockjaw" Davis, Eddie Harris, Houston Person, and Stanley Turrentine. Alto player Lou Donaldson was also an important figure.
Unlike hard bop, soul jazz generally emphasized repetitive grooves and melodic hooks, and improvisations were often less complex than in other jazz styles.
Probably the best known soul jazz recording is Ramsey Lewis's "The In Crowd," a major hit of 1965. Soul jazz was developed in the late 1950s, and was perhaps most popular in the early 1970s, though many soul jazz performers, and elements of the music, remain popular.