This study examines the relationship between psychiatric symptoms and violent/disruptive behavior among 192 inmates who participated in prison-based substance abuse treatment. Participants came from two sites able to provide narrative reports of disciplinary actions in the Criminal Justice Drug Abuse Treatment Studies' Co-Occurring Disorders Screening Instrument study. In multivariate logistic models, a lifetime history of thought insertion/control ideation (OR, 11.6; 95% CI, 1.8–75.2), antisocial personality disorder (OR, 3.3; 95% CI, 1.2–8.9), and disciplinary action related to possession of controlled substances or contraband (OR, 4.9; 95% CI, 1.9–12.3) were associated with increased risk for violent or disruptive behavior while in prison, whereas lifetime phobic symptoms (OR, 0.2; 95% CI, 0.1–0.54) and high school graduation (OR, 0.4; 95% CI, 0.2–1.0) were associated with a decreased risk of violence and disruptive behavior in general. We conclude that, among inmates in substance abuse treatment, symptoms that increase risk for violence or disruptive behavior include thought control/insertion ideation and disciplinary infractions related to controlledsubstances, contraband, or failure to participate in assigned programs, as well a history of antisocial personality disorder. Published in 2008 by John Wiley & Sons, Ltd.