This report describes the Ypsilanti Preschool Curriculum Demonstration Project, a 5-year program conducted to assess the efficacy of preschool intervention for culturally disadvantaged children diagnosed as functionally retarded. Five groups of 3- and 4-year-olds participated in the program or served as controls. The project served as a source of data for research on different types of preschool intervention and as a center for dissemination of information to teachers, administrators, and researchers in education. The curricula included: (1) a cognitively oreiented curriculum based primarily on Piaget's principles of cognitive development, the principles of sociodramatic play and impulse control suggested by Smilansky, and some specially developed language techniques; (2) a language training curriculum emphasizing learning of academic skills including arithmetic and reading; and (3) a unit-based curriculum emphasizing the social-emotional development goals of the traditional nursery school programs. The preschool sessions were supplemented with home visits. The results for the first two years of operation (1967-69) demonstrated that children may profit from any structured curriculum which offers a wide range of experience and individual student attention. (AJ)