This paper demonstrates the long-term intragenerational and intergenerational benefits of the HighScope Perry Preschool Project, which targeted disadvantaged African-American children. We use newly collected data on the original participants through late middle age and on their children into their mid-twenties. We document long-lasting improvements in the original participants' skills, marriage stability, earnings, criminal behavior, and health. Beneficial program impacts through the childrearing years translate into better family environments for their children leading to intergenerational gains. Children of the original participants have higher levels of education and employment, lower levels of criminal activity, and better health than children of the controls.

This paper quantifies and aggregates the multiple lifetime benefits of an influential high-quality early childhood program with outcomes measured through midlife. Guided by economic theory, we supplement experimental data with non-experimental data to forecast the life-cycle benefits and costs of the program. Our point estimate of the internal rate of return is 13.7% with an associated benefit/cost ratio of 7.3. We account for model estimation and forecasting error and present estimates from extensive sensitivity analyses. This paper is a template for synthesizing experimental and non-experimental data using economic theory to estimate the long-run life-cycle benefits of social programs.