The purpose of this study was to extend previous findings regarding the extratest validity of the Personality Assessment Inventory (Morey, 1991, 2007) scales and indicators in forensic contexts to an inpatient substance abuse setting. The Aggression Scale, and particularly the Physical Aggression subscale, related to assault history; the Suicide Scale and Suicide Probability Index related to history of suicide attempts; Antisocial Features, and particularly the Antisocial Behaviors subscale, predicted rule infractions; and the Treatment Process Index predicted treatment completion. We discuss clinical implications in the context of extant findings.