Utilization of health and mental health services by non-institutionalized persons aged 18 years and older is examined based on interviews with probability samples of 3,000 to 3,500 persons in each of three sites of the National Institute of Mental Health Epidemiologic Catchment Area (ECA) program: New Haven, Conn, Baltimore, and St Louis. In all three ECAs, 6% to 7% of the adults made a visit during the prior six months for mental health reasons; proportions were considerably higher among persons with recent DSM-III disorders covered by the Diagnostic Interview Schedule (DIS) or severe cognitive impairment. Between 24% and 38% of all ambulatory visits by persons with DIS disorders were to mental health specialists. In seeking mental health services, men were more likely to turn to the specialty sector than to the generalist; women used both sectors about equally. The aged infrequently received care from mental health specialists. Visits for mental health reasons varied considerably depending on specific types of DIS disorder.