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.
Fadeout is a pervasive phenomenon: post-test impacts on cognitive skills commonly decrease in the years following an educational intervention. Less is known, although much is theorized, about social-emotional skill persistence. The current meta-analysis investigated whether educational RCT impacts on social-emotional skills demonstrated greater persistence than impacts on cognitive skills among 87 interventions involving 59,237 participants and 443 outcomes measured at post-test and at least one follow-up. For post-test impacts of the same magnitude, persistence rates were similar (43% of post-test magnitude) across skill types for follow-ups occurring 6 to 12 months after post-test. At 1- to 2-year follow-ups, persistence rates were larger for cognitive skills (37%) than for social-emotional skills. Interestingly, smaller posttest impacts persisted at proportionately higher rates than larger impacts, which may benefit interventions measuring social-emotional outcomes given their smaller post-test impacts. Considered in whole, social-emotional and cognitive skills demonstrated similar patterns of fadeout.