"TSOP (The Sound of Philadelphia)" is a 1974 hit recording by MFSB (Mother, Father, Sister, Brother) featuring vocals by The Three Degrees. A classic example of the Philadelphia soul genre, it was written by Kenneth Gamble and Leon Huff as the theme for the American musical television program Soul Train, which specialized in African-American musical performers. The single was released on the Philadelphia International label.

The song is essentially an instrumental piece, featuring a lush blend of strings and horns in the Philadelphia soul style. There are only two vocal parts to the song: a passage close to the beginning during which The Three Degrees sing "People all over the world!"; and the chorus over the fadeout, "Let's get it on/It's time to get down". The words "People all over the world!" are not heard in the original version. "TSOP" hit number one on the U.S. Billboard Hot 100 in the spring of 1974 and remained there for two weeks. It also topped the American R&B chart (for one week) and adult contemporary chart (for two weeks). The Three Degrees would revisit the top of the AC chart later in 1974 with their hit single, "When Will I See You Again".

Although it was rerecorded a number of times for future versions of the show, "TSOP" has remained the theme song for Soul Trainthrough the disco, 1980s R&B, new jack swing, hip-hop, and neo soul eras of Black music.

"TSOP" was covered by Dexys Midnight Runners and released as a B-side on the 12" version of the "Jackie Wilson Said" single, later issued on the remastered version of the album Too-Rye-Ay. The band also used it to open some of their live shows.

Another cover was made in 1978 by reggae band Inner Circle, who had a history of covering American soul songs in the laid-back reggae style of the late 1970s.

The song is played at Citizens Bank Park in Philadelphia prior to every Phillies home game. Pilipinas, Game KNB?, a Philippines game show hosted by actor/politician Edu Manzano, used an adaptation of TSOP called "Papayo Yowza" as its theme.