Perry Preschool at 50: What Lessons Should Be Drawn and Which Criticisms Ignored?

The Perry Preschool Project, the longest-running experimental study of an early childhood education program, demonstrates how such interventions can yield long-term personal, societal, and intergenerational benefits for disadvantaged populations. The evidence is clear: investments in high-quality early childhood education and parental engagement can deliver returns even 50 years later. The program’s findings remain scientifically robust, particularly when analyzed through rigorous small-sample inference methods. The program’s findings also contradict common criticisms of preschool, as, when measured correctly, treatment effects on IQ do not fadeout. This paper draws insights from both the original founders and recent empirical studies, emphasizing the critical role of parental involvement in early education. The authors advocate for a scientific agenda focused on understanding the mechanisms behind treatment effects, rather than replicating specific programs. The analysis also underscores the broader implications of early childhood interventions for social mobility and human capital formation. Analysts of early childhood education should recognize that although credentials and formal curricula contribute to successful programs, the true measure of quality lies in adult-child interactions, which play an essential role.