Smooth soul is a style of Soul music that emerged in the USA in the mid-to-late 1960s. Initially developing from the Motown Sound, the genre reached its greatest height of popularity in the 1970s, exemplified by singles such as "Let's Get it On" by Marvin Gaye and "Me and Mrs. Jones" by Billy Paul. Smooth soul emphasizes slow tempo ballads with silky, often sensual, vocals and light, polished arrangements to create an intimate, romantic atmosphere. Specific musical traits include lush, sweeping string sections and piano, in contrast to the gritty, brass-dominated sounds of Southern Soul or the Psychedelic Rock-inspired keyboards and guitar in Psychedelic Soul. The underlying percussion and melodic basslines of smooth soul often showcase a light Funk influence, whilst common lyrical themes are love, sex and seduction.

From the mid-1970s onwards, it was associated with the American late night R&B radio show 'Quiet Storm', with singers such as Gaye, Al Green, Minnie Riperton, Barry White and Bill Withers given frequent exposure during this period. Due to similarly silky production styles, smooth soul overlaps with a large amount of Philly Soul, a distinct sound developed in Philadelphia by groups such as The Delfonics and Harold Melvin & The Blue Notes.

With the emergence of Contemporary R&B in the 1980s, smooth soul's prevalance gradually wavered, though singers such as Luther Vandross and Sade ensured the genre still maintained a relative degree of popularity. In the 1990s, D'Angelo, Maxwell and Erykah Badu combined smooth soul with elements of Hip Hop, contemporary R&B and funk to create the 'organic' sound of Neo-Soul.