This study used a structured diagnostic interview to investigate the prevalence of psychiatric comorbidity among 29 men and 23 women substance abusers residing in 1 of 11 Oxford House communities located within a Midwestern metropolitan area. The Diagnostic Interview Schedule (DIS) was used to measure current and lifetime DSM-III-R diagnosis in addition to sociodemographic and substance abuse information. Considerable psychiatric comorbidity was present. Antisocial personality (ASP) disorder, affective disorders, and anxiety disorders were the most frequently observed comorbid disorders among these substance abusers, whose drugs of choice were cocaine, alcohol, and cannabis. Chi-square and t tests revealed diverse psychiatric diagnoses and variability of client characteristics, demonstrating heterogeneity within this sample of substance abusers. Gender differences were identified on several client characteristics as well. Peer social support was the most common reason why participants entered an Oxford House. Outcome measures at 6 months found that 42% of participants was still residing in an Oxford House while 27% left on good terms, demonstrating a 69% overall success rate among participants in this study. Implications of this study suggest that substance abusers with psychiatric comorbidity are heterogeneous groups that benefit from living in an Oxford House.