It is now generally accepted that investments in high-quality preschools for low-income children can improve academic achievement and behavioral development, with significant reductions in future costs to government and society.1 Some have calculated that such investments can improve US economic productivity and competitiveness.2 While there is good evidence to support these conclusions, the estimate of exactly how much preschool can help is imprecise. What we can expect from preschool programs is limited in part by the small number of randomized controlled trials of preschool programs conducted in contemporary contexts and by the discrepancy between the model programs tested in randomized trials and the characteristics of most publicly funded preschool programs for low-income children in the United States today. Most estimates of the impacts of preschool are based on the results of 2 trials of model programs begun in the 1960s and 1970s (the Perry Preschool Program and the Abecedarian Project).3,4 These programs were exemplary. They were characterized by small class sizes, small child to teacher ratios, excellent teacher qualifications, well-crafted curricula, and investigator support for high-quality program implementation. They were also conducted outside of bureaucratic contexts, which can compromise the impact of innovative interventions.
Olds D. Improving Preschool for Low-Income Children With Programmatic Randomized Controlled Trials. Arch Pediatr Adolesc Med. 2007;161(8):807–809. doi:10.1001/archpedi.161.8.807