Reviewing the research findings and issues which have been generated around the topic of Mexican American underutilization of mental health services, this paper discusses five major concepts: (1) the epidemiological paradox of Mexican American underutilization of services; (2) explanation offered for the paradox; (3) elaboration on the explanation of incompatibilities of services; (4) examination of the conceptual problems involved in underutilization; and (5) discussion of recommendations for change. The paper discusses the findings which revealed that underutilization is not homogeneous; the concept of utilization is quite complex, and measures of need, accessibility and quality of services are needed to interpret utilization rate findings; and the concept of the existence of incompatibilities between the service delivery system and the characteristics of the clients holds the most conceptual promise. A two-tier approach is suggested which emphasizes both the concepts of equity and compatibility between clients' needs and the services provided. It is recommended that more research be done on total systems, including community involvement, funding agencies, service facilities, providers, and clients. (Author/JD)