What band was Jack Irons in before Pearl Jam?

Before Pearl Jam, Jack Irons was in the Red Hot Chili Peppers.

Irons was the Red Hot Chili Peppers’ founding drummer and part of the group’s original Los Angeles lineup. He played on The Uplift Mofo Party Plan, released in 1987, the only studio album featuring the band’s original four-member lineup of Anthony Kiedis, Flea, Hillel Slovak and Irons.

After leaving the Chili Peppers, Irons helped form the alternative-rock band Eleven and did not initially join the Seattle group that became Pearl Jam, despite being invited during its early formation. He did, however, pass a demo to his friend Eddie Vedder, helping connect Vedder with future Pearl Jam members.

Irons eventually became Pearl Jam’s drummer in late 1994 after Dave Abbruzzese’s departure. He recorded and toured with Pearl Jam until 1998, including work associated with Vitalogy, No Code and Yield. Matt Cameron later replaced him. Thus, Red Hot Chili Peppers is the canonical answer, even though Eleven was another important band in his career.