Supervision plays a key role in the provision of health and human services. An extensive literature exists on supervision as an element of professional development in behavioral health care. However, much less attention has been given to the practice of supervision in publicly funded systems of care for persons with mental and substance use conditions. This article provides a comprehensive review of the literature on supervision in the public sector, highlighting its current status, definition, functions, competencies, applicable standards and requirements, training approaches, and outcomes. Recommended strategies for restoring and advancing supervision as an essential practice in systems of care are discussed.