This article presents findings from a quasi-experimental, nonrandomized group design study that explored whether trauma-enhanced substance abuse treatment results in longer residential treatment stays and improved outcomes compared with treatment-as-usual. We used a subsample (N = 461) of participants in the Women, Co-Occurring Disorders and Violence Study, which was sponsored by the Substance Abuse and Mental Health Services Administration. The intervention group was 31% less likely to discontinue treatment within 4 months. Baseline mental health and trauma symptoms and alcohol and drug severity scores predicted neither overall length of time in treatment nor differences in retention between intervention and comparison groups. Substance abuse and mental health symptoms improved with increased duration of treatment, particularly for women with more severe baseline symptoms. (Contains 5 tables and 1 figure.)