This document is the first part of a comprehensive study designed to review existing data about child development and the evaluation data of programs for children in order to propose recommendations for Federal program planning. Two major goals of the work reported in this section (Volume 1 are: (1) to arrive at an adequate definition of "disadvantage," or more specifically, those kinds of factors in childhood for which Federal intervention seems warranted, and (2) to review the kinds of scientific evidence that might justify and direct government intervention. The section has six chapters. Chapter 1 is an introduction to the study, with discussion of the approach that is used. The notion of discrete public purposes as determinants of the larger goals of Federal programs is explained. Chapter 2 presents a historical review of American public programs, focusing around the public interests that are commonly behind the programs. Chapter 3 discusses research evidence that supports early intervention, as well as conflicting views on this issue. Chapter 4 analyzes data concerning connections between childhood events and outcomes in adolescence and adulthood. Chapter 5 reviews measurement indices available for evaluation of educational, child development, and family programs. Finally, chapter 6 offers a discussion of the health issues involved in intervention on behalf of children which parallels the preceding analysis of psychological and family intervention. (DP)