This paper explores historical and recent trends in the delivery of residential adolescent substance abuse treatment, looking specifically at the impact of managed care on the service delivery system. Three historical eras are conceptualized by the authors: (1) an era prior to managed care in which services were provided on a fee for service basis by health insurance companies and lengths of stay were relatively longer; (2) an era of managed care in which services were funded through managed care organizations and lengths of stay were significantly reduced; and (3) the current era in which residential services are provided through self-pay and through other service systems. Awareness of these changes is important for all practitioners who provide services to adolescents and demonstrate the need to advocates for residential substance abuse services for all adolescents.