This paper presents an overview of the evolution of the Yale University Child Study Center's School Development Program (SDP) since its implementation in New Haven, Connecticut in 1968. The needs of inner city school children are discussed, and results of parent and staff surveys are presented. A critique of alternative school improvement strategies is given, with particular emphasis on their limitations compared to SDP. Mental health correlates of school-related adjustment are discussed as are the principles, assumptions, and rationale for the ecological design of SDP. The specifics of implementing the program in New Haven are given, including the population and personnel, and results of research on the indirect and direct impact of SDP. The results of a 1982 pilot study are reported also, including data on social competence, achievement tests, and grade point averages. Prevention and public policy are discussed in regard to the court mandated implementation of SDP in the Benton Harbor, Michigan School District. A description of the Benton Harbor program, clarifying some of the complex issues and relationships among educational, psychological, and legal and community interest groups involved in the process of implementing the program, is provided. The paper concludes with a discussion of the implications for public policy of court-ordered prevention programs. Two figures are appended to illustrate the SDP model and the implementation process in the Benton Harbor schools. (BL)