The Substance Abuse and Mental Health Services Administration (SAMHSA) funded the Women, Co-Occurring Disorders and Violence Study to generate empirical knowledge on how to improve services for women who are trauma survivors and have co-occurring mental health and substance use disorders. We first review the literature on the pervasiveness of trauma among women and the ways in which current service systems fail to address their needs. We then describe the four core principles of the model grantees developed to test in the project. Working through a project Steering Committee, grantees mandated that services be (a) integrated, (b) trauma-informed, (c) consumer-involved, and (d) comprehensive. For each of these principles, we describe the specifications adopted by the committee, the strategies the study sites used to implement the principle in their local settings, and the concrete lessons sites learned concerning how to implement the principle. © 2005 Wiley Periodicals, Inc. J Comm Psychol 33: 395–410, 2005.