MFSB (according to the "clean" interpretation, Mother Father Sister Brother) was a pool of more than thirty studio musicians based at Philadelphia’s famed Sigma Sound Studios. They worked closely with the production team of Gamble and Huff and producer/arranger Thom Bell, and backed up such groups as Harold Melvin & the Blue Notes, the O’Jays, the Stylistics, the Spinners, Wilson Pickett, and Billy Paul.