Undertaken as a background paper for an early childhood education policy study intended to identify current issues in early childhood education and policy alternatives for consideration by the State Board of Education of Illinois, this report focuses on the effectiveness of early childhood education programs. Specifically addressed are (1) reasons commonly advanced for offering education at an early age, (2) indicators of program effectiveness, (3) types of programs and program characteristics in the light of their relative effectiveness, (4) the SES of children who benefit from programs, and (5) the developmental role of early childhood education programs in the child's learning environment. A review of research for each of the following topics is covered in the paper: rationale for early childhood education, indicators of program effectiveness (including IQ, scholastic achievement, scholastic placement, non-cognitive development, and social responsibility), types of characteristics of programs (including leadership, program duration, adult-child ratio, curriculum, continuity, program location, and parent involvement), the SES difference of children in relation to benefits from early childhood education, and the learning environment. (DST)