Clinical supervision itself is much discussed in the professional literature of several disciplines, including social work, psychology, and both mental health and substance use disorder counseling. Theories, process dynamics, and tools abound, but the functional responsibilities and essential skills of the substance use disorder treatment supervisor had not been synthesized into one document that could serve as a standard for the field. To remedy that situation, CSAT convened the Clinical Supervision Competencies Task Force (the Task Force) in fall 2005. The Task Force, composed of experts in substance abuse treatment and clinical supervision from across the country, was charged with developing this document, TAP 21-A, Competencies for Substance Abuse Treatment Clinical Supervisors. TAP 21-A is designed to accompany TAP 21, taking monitoring, assessment, and improvement of addiction counseling competencies to the next level.