This study quantified the benefits to children and parents participating in nine early intervention programs and conducted a cost-benefit analysis of the Perry Preschool and the Elmira Prenatal/Early Infancy Project (PEIP). The findings indicated that early intervention programs led to the following advantages for program participants relative to those in the control groups: (1) gains in child emotional or cognitive development or improved parent-child relationships; (2) improvements in educational process and child outcomes; (3) increased economic self-sufficiency, initially for parents and later for children; (4) reduced criminal activity; and (5) improvements in health-related indicators. Savings to government programs were much higher than the costs for the Perry Preschool; this was also true for the higher-risk families of the PEIP. For lower-risk participants of the PEIP, however, government savings were not enough to offset program costs. (Two appendices detail the benefit cost analysis. Contains 159 references.) (KB)