One of 10 documents developed for preschool programs for handicapped children, the document reports a study of the long term effectiveness of the preschool program supported by the Board of Cooperative Educational Services in Putnam/Northern Westchester (New York). The study evaluated the impact of the program on 66 children in the areas of later school placement, rate of retention, requirement for special services, teacher ratings, parent ratings, and persistence of effect. Results showed the long term effectiveness of the program in findings indicating that the preschool program graduates are performing adequately in school, progressing normally through the grades, socializing well with their peers, requiring a minimal amount of special services, and achieving at a similar level to their peers in cognitive and academic areas. The children were rated as having very positive attitudes toward school by both their teachers and parents. (DB)