Impacts of Oversubscribed Boston Pre-K Programs through Middle School

In this pre-registered study, we explored the impacts of Boston Pre-K on children’s educational trajectories, school progress/engagement, and academic achievement in late elementary and middle school using lotteries for oversubscribed schools in 2007-2011 (N=3,092 students; 24% of all applicants). Importantly, the program was unique nationally in its strong supports for teachers and in its use of evidence-based curricula. Nearly all control-group children attended other preschool programs. Treatment compliers had markedly different educational trajectories than control compliers in grades 4-8. Treatment compliers were much more likely to be enrolled in the Boston Public Schools, less likely to be enrolled in charter schools (especially in late elementary school), and less likely to transition schools in 6th grade. Treatment compliers were 14 percentage points more likely to apply to Boston’s competitive exam schools, which begin in the 7th grade (p<.10); they were also 10pp more likely to be admitted and 5pp more likely to enroll, though neither of these latter differences was statistically significant. These differential 6th and 7th grade transitions aligned with when larger differences by treatment status emerged on some outcomes. For example, suspension rate differences were small in 4th and 5th grades, but increased (favoring the treatment group) in the 6th and 7th grades, though only the 7th grade difference was statistically significant (i.e., treatment compliers were 7.6 percentage points less likely to be suspended in 7th grade; p<.05). For achievement, we found patterns favoring treatment compliers for both math and reading tests beginning in 5th grade and increasing in 6th and 7th grade, though only the 7th math effect (d=0.24 SD; p<.05) was statistically significant. Treatment compliers also enrolled and passed Algebra I by the end of 8th grade at a much higher rate than control compliers (22.6 percentage points, p<.01). We found no meaningful impacts on students’ in-grade retention, special education placement, or attendance. Generalizability analyses suggested larger benefits for the full sample of BPS Pre-K applicants. Findings shine new light on longitudinal Pre-K effects in the developmentally turbulent middle school years, especially in crowded school choice environments.