This article reviews the existing research base for child mental health services and policy. It emphasizes the importance of research that looks at the overall community-based system of care as the unit of analysis, and stresses the need to maintain a systems perspective, even when research is focused on components of the overall system. The review concludes that there is a need for a considerable increase in child mental health services research but also indicates that there has been a recent increase in research that has the potential of building a base to change policy. In particular, a need is identified for well-controlled studies that assess both clinical and cost outcomes and for studies that examine the mega issues of the organization and financing of systems of care.