OBJECTIVE: To study the ways in which allocating the risk for behavioral health care expenses between employers and a managed behavioral health organization affects costs and the use of services. DATA SOURCES: Claims from 87 plans that cover mental health and substance abuse services covering over one million member years in 1996/1997. STUDY DESIGN: Multi-part regression models for health care cost are used. Dependent variables are health care costs decomposed into access to any care, costs per user, any inpatient use, costs per outpatient user, and costs per inpatient user. The study compares full-risk plans, in which the managed care organization provides managed care services and acts as the insurer by assuming the risk for claims costs, with contracts in which the managed care organization only manages care (for a fixed administrative fee) and the employer retains the risk for claims. PRINCIPAL FINDINGS: Full-risk plans are not statistically significantly different from non-risk plans in terms of any mental health specialty use or hospitalization rates, but costs per user are significantly lower, in particular for inpatients. CONCLUSIONS: Risk contracts do not affect initial access to mental health specialty care or hospitalization rates, but patients in risk contracts have lower costs, either because of lower intensity of care or because they are treated by less expensive providers.