"If You Don't Know Me by Now" is a song written by Kenny Gamble and Leon Huff, and recorded by the Philadelphia soul musical group Harold Melvin & the Blue Notes. It became their first hit after being released as a single in September 1972, topping the US R&B chart and peaking at number 3 on the US Billboard Hot 100.

Kenneth Gamble and Leon A. Huff are an American songwriting and production team credited for developing the Philadelphia soul music genre of the 1970s. In addition to forming their own label, Philadelphia International Records, Gamble and Huff have written and produced 175 gold and platinum records, earning them an induction into the Rock and Roll Hall of Fame in the non-performer category in March 2008.