I think I first heard this song in Sister Act 2
This song has a great story. It's based on a much older hymn, but Edwin Hawkins wrote this arraignment for the Northern California State Youth Choir of the Church of God in Christ. He was the musical director of the 50 member choir. They needed money to get to a youth congress in DC so they recorded an eight song record and pressed 500 copies to sell as a fundraiser. One of those records got into the hands of a San Francisco DJ who began to play Oh Happy Day on his underground station and it became a local favorite, being requested on other area radio stations. A record producer heard the track and bought the national distribution rights. He renamed the group The Edwin Hawkins Singers. The song was a hit, and has been covered by gospel, folk, R&B and country singers.
The instrumentation is simple: piano, bass, drum set. Then you've got the big choir, and lead vocals by future gospel star Dorothy Coombs Morrison. The instruments don't even take a back seat here, more like the jump seat in the back of a station wagon. I don't mean they aren't important, they do make sure the piece rocks, but it is all about that big vocal sound. When they all break out you can't help but nod along.