California Jam, also known as Cal Jam, was a rock music festival co- headlined by Deep Purple and Emerson, Lake & Palmer and held at the Ontario Motor Speedway in Ontario, California, USA, on April 6, 1974.
It was produced by ABC Entertainment, Sandy Feldman and Leonard Stogel. Pacific Presentations, a Los Angeles-based concert company headed by Sepp Donahower and Gary Perkins, coordinated the event, booked all the talent and ran the advertising. Don Branker worked for Leonard Stogel and was responsible for concert site facilitation, toilets, fencing and medical. It attracted 250,000 paying fans. The festival set what were then records for the loudest amplification system ever installed, the highest paid attendance, and highest gross in history. It was the last of the original wave of rock festivals.
Deep Purple's performance was one of the first with their third line-up, which included the vocalist David Coverdale and the vocalist/bass guitarist Glenn Hughes.