One Nation Under a Groove is the tenth studio album by American funk rock band Funkadelic, released on September 22, 1978, on Warner Bros. Records. Recording sessions took place at United Sound Studio in Detroit, with one song recorded live on April 15, 1978, at the Monroe Civic Center in Monroe, Louisiana. The album was the first album to include keyboardist and frequent songwriter Walter "Junie" Morrison.

One Nation Under a Groove was Funkadelic's most commercially successful album, reaching number 1 on the Billboard Magazine Top R&B/Hip-Hop Albums chart, number 16 on the Billboard 200, and being certified platinum in the US. It reached number 58 in Canada. It was praised by critics, and appears in several "best album" lists. It was featured on Vibe magazine's 100 Essential Albums of the 20th Century and 51 Essential Albums lists. The album was ranked number 177 on Rolling Stone magazine's list of the 500 greatest albums of all time in both 2003 and 2012 editions, before moving to number 360 in the 2020 edition. The album is listed as one of the 1001 Albums You Must Hear Before You Die.