Jack's musical beginnings happened at Bancroft Jr. High and Fairfax High where he became friends and musical partners with the late Red Hot Chili Pepper guitarist Hillel Slovak, Eleven singer/guitarist Alain Johannes, bassist Flea and vocalist Anthony Kiedis. What Is This emerged in 1980 and played extensively for many years in the LA area which led to the MCA Records releases of Squeezed and What Is This.

1983 was the birth year of the Red Hot Chili Peppers. They too played extensively in the LA area with Jack on drums until they were signed to EMI Records in 1983. Jack continued with What Is This until 1986. He rejoined the Red Hot Chili Peppers in 1986 and played with them until the summer of 1988. Those years included the making of The Uplift Mofo Party Plan.

In 1990 Jack reunited with Alain Johannes and new musical partner Natasha Shneider to form Eleven. Eleven released 3 records with Jack: Awake In a Dream, Eleven and Thunk. He rejoined Eleven in 2003 for the release of Howling Book. In 1989 Jack recorded for Joe Strummer's Earthquake Weather. A tour of that record was done in the summer/fall of 1989. On that tour he met vocalist Eddie Vedder. Introducing Eddie to the music of Stone Gossard, Jeff Ament and Mike McCready led to the beginnings of Pearl Jam. In the fall of 1994 Jack joined Pearl Jam and played with them through the spring of 1998. His work with Pearl Jam included the releases of Merkinball, No Code, Yield and the Neil Young-Pearl Jam collaboration Mirrorball.

In 2004 Jack released his first solo record Attention Dimension. In the years since he has performed on records for Spinnerette, Die Mannequin, Hole and Mark Lanegan. His 2nd solo record entitled No Heads Are Better Than One was released in August of 2010 and the Blue Manatee EP, the 3rd solo record came out in 2011. Jack recorded Glad All Over with The Wallflowers in early 2012 and toured with them thru August of 2013. Arthur Channel is a new project with Greg Richling, Jon Greene and Alain Johannes. Arthur Channel's record was released October 2013. Jack was inducted into the Rock and Roll Hall of Fame with the Red Hot Chili Peppers in April of 2012.