Consistent with the priority goals of the 2002 Future of School Psychology Conference, the National Association of School Psychologists' "Blueprint for Training and Practice III" advocates for school psychologists becoming "leading mental health experts in schools." In this regard, the present article reviews the prevalence and incidence of children's mental health problems in the schools, followed by a historical overview of the nature of school-based mental health services. We discuss education and training issues and related ethical and professional practice issues that focus on the ethics codes of the National Association of School Psychologists and the American Psychological Association that are associated with the delivery of mental health services by school psychologists. Recommendations are offered for graduate-level coursework and field experiences in the delivery of school-based mental health services, as well as future directions for research in this area. (Contains 2 tables.)