Historically social work has had a significant presence in the field of addiction treatment. The profession’s unique bio-psycho-social-spiritual perspective requires practitioners to attend not only to the major presenting problem of an individual but also to the personal and social issues that affect an individual’s fimctioning. The number of people in need of drug treatment services has increased significantly in recent years. In addition, individuals who enter treatment for drug disorders often present with serious co-occurring problems such as medical conditions, mental health issues, family troubles, lack of adequate housing or employment and criminal justice involvement. Often, the nature and severity of these problems require additional supportive services beyond the core addiction treatment services. The purpose of this research was to explore the relationship between the availability of supportive services and successful client outcomes from an organizational perspective. The research was guided by an adaptation of Scott’s (1998) model of organizational analysis which was adapted from Leavitt’s (1965) organizational change in industry model. This research project was a secondary analysis of data collected on 71 drug treatment programs located in 11 large metropolitan areas in the United States. The major hypotheses were, #1: Drug abuse treatment programs that offer a greater number of R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. PREVIEW on-site supportive services will evidence higher rates of successful client program completion, #2: Organizational structural variables (i.e. modality, program size, average caseload size, size of professional staff, and social work staff) will influence the degree to which programs offer supportive services that in turn will influence the rate of successful client program completion.