MFSB, short for Mother Father Sister Brother, was a prominent American soul music orchestra active from the early 1970s to the mid 1980s. Known for their instrumental work, they were the in-house band for Philadelphia International Records, contributing significantly to the distinctive Philly soul sound. Their most famous composition is "TSOP (The Sound of Philadelphia)", which was adopted as the theme song for the television show "Soul Train". MFSB's fusion of orchestral soul, funk, and disco has influenced numerous artists in the R&B and dance genres.