Data from the NIMH-Epidemiologic Catchment Area Project were used to predict differential use of private versus public outpatient mental health services, a salient concern in integrating public and private services in market-based health care reform efforts. Having a recent psychiatric disorder, being age 25-44, female, white, of higher educational level, and unmarried increase the odds of any mental health service use. However, odds of treatment in the public sector are increased for males, African Americans, those with low educational and income levels, and odds are markedly decreased for the elderly, suggesting significant barriers to care for these mentally ill subpopulations.