This volume presents a summary of the methods, findings and recommendations for federal policy of the National Day Care Study (NDCS), a 4-year study of the effects of regulatable day care center characteristics on the quality and cost of day care for preschoolers. Chapter I describes current day care services and the history of federal involvement to the present. Chapter II presents the major policy issues addressed by the NDCS and its conceptual framework and research design. Chapter III explains the sampling procedure of the NDCS. Chapter IV deals with those aspects of day care centers which are susceptible to federal regulation and hence most affected by federal policy decisions, and with alternative measures of policy variables. Chapter V discusses the conceptual and instrumental problems of defining "quality care" and gives the study's definition. Chapters VI and VII present the NDCS findings. In Chapter VI the relation between regulatable aspects of day care and quality of care, the generality of the findings, and the connection between research findings and policy decisions are explored. In Chapter VII the issue of cost versus quality is examined. Chapter VIII discusses current regulatory policy and recommends alternative regulatory policies. A "Commentary" is appended which presents the views of minority consultants on issues with crucial effects for minority children. Three appendices provide: (1) a summary of the findings of the NDCS Supply Study, (2) an overview of the Infant/Toddler Study, and (3) the names of all NDCS staff and consultants. (Author/BH)