"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, which became their first hit after being released as a single in 1972, topping the R&B chart and peaking at number three on the Pop chart.[1]
The song was originally written for Labelle (a trio led by Patti LaBelle) but they never recorded it. After some revisions, the song was offered to The Dells but they also never recorded it. Harold Melvin & the Blue Notes signed to Gamble & Huff's own Philadelphia International label in 1971 and they did record the song, with the late Teddy Pendergrass as lead vocalist. In addition to the single release, the song was included on their eponymous debut album."