The general mission of the proposed Center for Therapeutic Community Evaluation Research (CTCER) is to advance the scientific knowledge base concerning the therapeutic community approach to the treatment of chemical dependency and related problems. This mission would be pursued through evaluation- research studies and center core activities designed to promote evaluation- research capability with the broader TC modality and to expand the utilization of research for practice. The major aim of the proposed Center is to conduct a systematic program of evaluation-research studies with three significant themes: the effectiveness of TC treatment for special populations in special settings, the TC treatment process, and treatment improvement/special issues (e.g., retention, client treatment matching, short- and long-term planned duration of treatment). The theme of the present submission is special populations. Three separate studies would evaluate the effectiveness of the TC model adapted for: criminal substance abusers within a state correctional institution, mentally ill/homeless chemical abusers (MICA) in community residence mental health settings, and adolescent substance abusers in community-based residential TC programs.