National attention to the effects of interpersonal trauma has led mental health systems to adopt policies on trauma-related services; however, there is a lack of clarity regarding targeting of these services. Data from the Women, Co-occurring Disorders and Violence Study (WCDVS) were reanalyzed by grouping women on their baseline PTSD and substance abuse presentation and assessing the differential response to an integrated mental health/substance abuse intervention. Treatment effects were largest for subgroups characterized by high levels of PTSD, whereas the effects for those in the low symptom group were near zero. These findings underscore the need for clinicians to conduct careful assessments of trauma-related symptoms and to target the most intensive trauma-related interventions to individuals with PTSD symptoms.