The proposed expansion of early childhood services to disadvantaged children will, the committee acknowledges, require a substantial investment. Few programs collect longitudinal data that would allow for a careful cost-benefit analysis. Two programs—the Perry Preschool program and the Prenatal and Infancy Home Visitation by Nurses—have done longitudinal data collection that indicates benefits outweigh costs by several times when long run effects on crime and teenage pregnancy are considered (Karoly et al., l998). Those results should not be projected onto large-scale intervention programs for many reasons, among them the change in both costs and benefits as program size increases dramatically and the characteristics of the population changes. The results do suggest, however, that up front investment in changing a developmental trajectory produces benefits over a life course with implications for government revenues as well as for individual success.