Perry Preschool Study
Lifetime Effects: The HighScope Perry Preschool Study Through Age 40 (2005)
This study — perhaps the most well-known of all HighScope research efforts — examines the lives of 123 children born in poverty and at high risk of failing in school.
From 1962–1967, at ages 3 and 4, the subjects were randomly divided into a program group that received a high-quality preschool program based on HighScope’s participatory learning approach and a comparison group who received no preschool program. In the study’s most recent phase, 97% of the study participants still living were interviewed at age 40. Additional data were gathered from the subjects’ school, social services, and arrest records.
The study found that adults at age 40 who had the preschool program had higher earnings, were more likely to hold a job, had committed fewer crimes, and were more likely to have graduated from high school than adults who did not have preschool. See figures below for more information.

High IQ at 5 linked to success in life at 40