Objective/Method: Given the relationship between post-traumatic stress disorder (PTSD) and substance use disorders (SUD), and the prevalence of SUD among offenders, the inattention to trauma before, during, and after incarceration is troubling. This exploratory study compared those with and without co-occurring PTSD among men (n = 139) and women (n = 60) involved in prison-based substance abuse treatment. Results: More than one half the sample met criteria for lifetime PTSD with women experiencing a greater number of events and men experiencing more recent events. Women with PTSD were significantly more likely to relapse than women without. Men with PTSD were more likely to enter community aftercare treatment and recidivate than those without. Conclusion: The findings suggest that trauma-related disorders, among those with SUD, affect postincarceration outcomes. Therefore, from a practice and policy perspective, interventions addressing this co-occurring disorder should be available to men and women within the criminal justice system. (Contains 3 tables.)