The album takes its name from the band's habit of starting their performance at 8:30 pm. At the time of the tour, the band was a quartet and would take the stage continuously for around two and a half hours, each of the members taking a solo. Wayne Shorter sometimes plays percussion instead of saxophone on stage, and on one of the studio tracks, the calypso inspired "Brown Street", Joe Zawinul's son Erich plays percussion with Erskine and Pastorius.
According to Peter Erskine, the band had planned for the entire album to be live, but an engineer accidentally erased some of the material, prompting the band to go into the studio to record the fourth side.
The album was originally a double gatefold LP. The reissue on CD dropped "Scarlet Woman" and was released as a single CD. In Japan, the album was released as a 2-CD set with all the tracks of the original.