High-quality preschool programs are heralded as effective policy solutions to promote low-income children’s development and life-long wellbeing. Yet evaluations of recent preschool programs produce puzzling findings, including negative impacts, and divergent, weaker results than demonstration programs implemented in the 1960s and 70s. We provide potential explanations for why modern preschool programs have become less effective, focusing on changes in instructional practices and counterfactual conditions. We also address popular theories that likely do not explain weakening program effectiveness, such as lower preschool quality and low-quality subsequent environments. The field must take seriously the smaller positive, null, and negative impacts from modern programs and strive to understand why effects differ and how to improve program effectiveness through rigorous, longitudinal research.
Prior research has found that financial investments in North Carolina’s pre-kindergarten (pre-K) program generated positive effects on student reading and math achievement through eighth grade (Bai et al., 2020). The current study examined the interaction between NC Pre-K funding and two key dimensions of the subsequent educational environment students experience in their school districts: average achievement and achievement growth. In relation to student reading and math achievement in eighth grade, the benefits of NC Pre-K funding were found to be additive to the benefits of school-district average achievement. The benefits of NC Pre-K funding were also found to interact with the benefits of school-district achievement growth such that the NC Pre-K effect was larger in school districts with lower rates of growth in academic achievement. These findings suggest that public investments in early childhood education may be particularly beneficial in the long term for children who subsequently experience low-growth schooling environments compared to children in high-growth environments.