OBJECTIVE: The study evaluated the impact of Medicaid managed care on decision making during emergency mental health screening and the outcomes of such screening for children and adolescents. METHODS: Data on client attributes and on system characteristics (payer, referral source, and disposition) were available for 297 Medicaid and non- Medicaid episodes of emergency mental health screening that occurred one year before the implementation of a statewide managed Medicaid program in Massachusetts and 393 episodes that occurred one year after implementation. Outcomes included changes in the volume of service provided and in the pattern of dispositions, particularly inpatient admissions. RESULTS: Although the total volume of child and adolescent emergency screening episodes significantly increased after implementation of Medicaid managed care, inpatient admissions decreased significantly. Among episodes not covered by Medicaid, no significant changes were noted after implementation on any variables. In the Medicaid group, significant differences were found in client attributes and system characteristics. After implementation the volume of emergency screening episodes for Medicaid clients increased significantly, and inpatient admissions decreased significantly. The pattern of dispositions changed significantly, with increased use of newly available crisis stabilization services. CONCLUSIONS: Although implementation of Medicaid managed care achieved the short-term goal of a decrease in hospitalizations, and probably concomitant savings, issues of quality of care for children and adolescents, and savings over the longer term, remain to be addressed.