Information on the preschool years, which has emerged from the pioneering studies and programs of the 60's, is reviewed and interpreted with regard to implications for current and future policy. Limitations of knowledge in this area are noted and attributed to inadequacies in the related research. Four general findings are reviewed and discussed: (1) The importance of the first 6 years of life incorporates research on prenatal development and infants' motor, cognitive, and linguistic abilities. (2) There exists a diverse technology for teaching families of young children. Included are an overview of experimental programs concerned with cognitive development and school achievement, a review of the Head Start literature, and a tentative comparison of the relative effectiveness of different approaches to early experience derived from the Planned Variation Study. (3) Continuity of human development is vital to maximize program effects. Methods are suggested that might provide continuity between preschool and primary school experiences. (4) The importance of multiple influences on children are reaffirmed. There is a need for alternatives that strengthen the family as the primary childrearing agent, instead of encouraging families to place their children in day care. (DP)