In order of appearance, the following performed:
The event was MC'd by New York DJ Don Imus.
Deep Purple's performance was one of the first with their third line-up, which included vocalist David Coverdale and vocalist/bassist Glenn Hughes. Deep Purple was given the choice of when to go on stage, and chose sunset, thus pushing Emerson, Lake & Palmer to the last performance. Having assumed that, as with all festivals, the show would run late, they nonetheless delayed their appearance even when the festival ran ahead of schedule. Angry organizers tried to force Purple onstage, and threatened to cancel their performance. A quick thinking announcer told the crowds that Deep Purple would be on "soon". The band made concertgoers wait nearly an hour until near dusk. Guitarist Richie Blackmore said the agreement was always for Purple to go on stage at dusk, and that the promoters were violating thatsigned agreement. In spite of this delay, the show did not end up running late. At the end of Purple's set, Blackmore threw a guitar and a small speaker monitor into the audience, and suddenly attacked one of the network's video cameras (the camera had been getting between the guitarist and the audience) with a guitar. Later on, a mishap with a pyrotechnic effect caused one of Blackmore's amplifiers to explode, which briefly set the stage on fire. Purple left the concert area by helicopter to avoid a possible confrontation with Ontario fire marshals and ABC-TV executives. The damage to the ABC video camera, estimated to be $10,000, was settled by the band's managers.
The weather on the day of the Cal Jam concert was unusually warm for April. At one point in the late afternoon, thousands of plastic gallon jugs were handed out to the audience, who were able to fill the jugs up at the many drinking fountains set up on the grounds. During the prolonged delay waiting for Deep Purple to hit the stage, restless concert goers began tossing their water jugs in the air. More and more of the audience joined in, until the air above the crowd was filled with hundreds of water jugs flying around, spraying water over the audience.
Deep Purple's California Jam performance, along with some of the performances by other bands, was broadcast on TV and radio nationwide in the US. It was at this festival that the footage of Keith Emerson playing a grand piano spinning end-over-end 50 feet above the ground was taken.
For the Eagles' set, Jackson Browne deputized for absent guitarist Don Felder, whose wife was giving birth to their first child.
Circus reported that Emerson, Lake & Palmer were "angry with the Deep Purple boys, who refused to come onstage until darkness fell. ELP subsequently couldn't begin their set until after one a.m."