Perry Preschool Project
Ypsilanti Public Schools / High/Scope Educational Research Foundation · Ypsilanti, Michigan, USA · 1962
Summary
The Perry Preschool Project is the most influential early childhood intervention study in existence. Followed for over 40 years, children randomly assigned to receive two years of high-quality preschool outperformed controls on every major life outcome measured: education, employment, income, and criminal justice. The benefit-cost analysis—$7 returned for every $1 invested—became the standard argument for early childhood investment. The study's longevity and breadth of outcomes make it uniquely persuasive as a policy argument.
Research question
"Does high-quality preschool education for disadvantaged children produce lasting benefits into adulthood?"
Methodology
Intervention
Daily classroom sessions + weekly home visits for 2–3 year-old children from low-income African American families; high-quality active learning curriculum
Assignment
Randomized controlled trial (child)
Sample size
123 children (58 treatment, 65 control), followed to age 40+
Primary outcome
Educational attainment, employment, earnings, criminal justice involvement at multiple adult follow-ups
Effect estimate
By age 40: treatment group had higher graduation rates (+23 pp), higher employment (+26 pp), higher median earnings (+42%), lower arrest rates (−22 pp); estimated benefit-cost ratio of 7–12:1
Decision
Foundational evidence for Head Start expansion and preschool investment nationally; cited in virtually every early childhood policy debate
Result
Positive
By age 40: treatment group had higher graduation rates (+23 pp), higher employment (+26 pp), higher median earnings (+42%), lower arrest rates (−22 pp); estimated benefit-cost ratio of 7–12:1
Evidence strength
Strong
Randomized controlled trial with large sample.
Replication status
Partially replicated
Institution
Ypsilanti Public Schools / High/Scope Educational Research Foundation
Location
Ypsilanti, Michigan, USA
Year
1962
Policy area
Early Childhood
Mechanism
Human capital