The authors examine the use of two sets of criteria, both dealing with substance abuse level‐of‐care determinations, yet having two different functions, and frequently yielding different decisions: The Green Spring Health Services (GSHS) Medical Necessity Criteria for Utilization Management and The American Society of Addiction Medicine (ASAM) Patient Placement Criteria. The GSHS criteria are used for rendering medical‐necessity determinations for individuals covered under a managed care program. These determinations involve assigning the least restrictive and least intensive level of care capable of meeting the patient's needs through the use of the complete continuum of treatment service options, including outpatient detoxification, intensive outpatient programs, partial hospitalization programs, and supervised residential settings. The ASAM criteria are oriented toward treatment planning within substance abuse settings to coordinate patient placement between levels of care within a treatment program.