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Intergenerational and Intragenerational Externalities of the Perry Preschool Project

NCJ Number
James Heckman; Ganesh Karapakula
Date Published
27 pages

This paper examines the impact of the Perry Preschool Project early childhood program on the children and siblings of the original participants, to determine intergenerational treatment effects on education, employment, and crime.


This document presents an examination of the Perry Preschool Project on the children and siblings of the original, treated participants. Research results demonstrated that the children of treated participants have fewer school suspensions, higher levels of education and employment, and lower levels of participation in crime, compared with the children of untreated participants. Impacts were especially pronounced for the children of male participants, and treatment effects were associated with improved childhood home environments. The intergenerational effects occurred even though families of treated subjects live in similar or worse neighborhoods than control families. Similar effects were observed for the siblings who did not directly participate in the program, especially male siblings of participants. In this paper, the authors examine features of the data on the children of participants; propose solutions to address a major limitation of their data; define the parameters of their research methodology; discuss their econometric methods; and address the potential problem of fertility choices by the Perry participants, noting it does not appear important in their sample. The authors present their estimates of intergenerational externalities, discuss the early environments of the children of participants, and discuss the impact of the program on participants’ siblings who were ineligible to participate in the program. The authors found that intergenerational and intragenerational externalities of the Perry Preschool Project are of first-order importance, and spillover treatment effects are especially strong for male children and siblings of participants. The authors also found strong intergenerational effects on female and male children of male participants, and that family structure is likely more important than neighborhoods when accounting for intergenerational treatment effects. The authors suggest that those types of programs can contribute to lifting multiple generations out of poverty.