D.I. is a Southern California punk band featuring ex-Adolescents and Social Distortion drummer Casey Royer on vocals. Royer formed the group after he and former Social Distortion original member Rikk Agnew (also formerly of Christian Death), left the original Mike Ness crew.
Since forming in 1982, D.I. has had many line-up changes and Royer has been the only constant member of the band. The band once broke up and reformed, sometimes with former members of The Adolescents and Social Distortion (including the Agnew brothers Rikk and Alfie). During their years of touring and recording albums, D.I. never gained a large mainstream success, but they have influenced many of today's later punk rock groups, including F.T.E.,Face to Face, Guttermouth, Jughead's Revenge, The Offspring and Pennywise.