This DataWatch analyzes the effect of the Utah Prepaid Mental Health Plan (UPMHP) on use of mental health services by and mental health treatment expenditures for Medicaid beneficiaries from July 1991 to June 1992. During this period three community mental health centers (CMHCs) provided mental health services to Medicaid beneficiaries in their catchment areas in return for capitated payments. Utilization and expenditure rates per beneficiary per month were analyzed using a "fixed-effects" statistical modeling approach, controlling for categories of beneficiary, time trends, seasonal effects, and CMHC grouping (capitated urban, capitated rural, noncapitated urban, and noncapitated rural). The results of the analysis suggest that the UPMHP reduced admissions for inpatient mental health treatment, inpatient mental health expenditures, and total mental health expenditures for Medicaid beneficiaries. These findings must be regarded as preliminary because of the relatively short time period covered by the data.