This column examines the major reasons for nonpsychiatric inpatient stays in the Medicaid mental health service user population. Data are from the Center for Medicare and Medicaid Services' State Medicaid Research Files. A total of ten states—Alabama, Arkansas, Delaware, Georgia, Kansas, Kentucky, New Hampshire, New Jersey, Vermont, and Wyoming—were included. The study group consisted of nonelderly Medicaid recipients who used mental health and substance abuse services in 1995. Individuals who were enrolled in both Medicaid and Medicare and those in managed care programs were excluded because of limited information about their service use. Additional details about the population and methodology have been published elsewhere (1).