MFSB (short for "Mother, Father, Sister, Brother") were a loose conglomeration of studio musicians who provided backing tracks for dozens of seminal Philadelphia soul recordings in the 1970s, and later released successful songs and albums as a standalone recording act.

Assembled by the production team of Gamble & Huff, MFSB was the house band for their Philadelphia International Records label and provided the signature smooth Philadelphia sound for many acts including the O'Jays, The Spinners, Harold Melvin & the Blue Notes, and The Stylistics.

In 1974, Philadelphia International released an instrumental track which had been recorded by the band as the theme for the television show Soul Train as a single. The record, titled "TSOP (The Sound of Philadelphia)" was a hit on both the pop and R&B charts, and launched a recording career for the band under their own name. MFSB albums and singles were released for the rest of the decade, and their material later served as ample material for sampling by hip-hop musicians