Research indicates that one or more years of high-quality, developmentally appropriate early care and education (ECE) improves a range of children's outcomes, including language, literacy, and numeracy skills, when measured at the end of the program or soon after. These findings are consistent across small demonstration programs, such as the well-known Perry Preschool and Abecedarian programs, which have shown very large effects, as well as among large-scale public programs such as public pre-K and Head Start programs. The large-scale public programs have shown positive but more modest short-term effects, but they were also, in general, less costly or intensive, and served a broader range of children.
Relatively recent research on the impact of high-quality prekindergarten programs on children's outcomes is quite strong, providing evidence for both short- and long-term impacts of meaningful magnitude. Pre-K yields large short-term effects on academic measures of school readiness (e.g., cognition, language), and some studies show that pre-K programs improve social-emotional development. For example, research on Oklahoma's universal prekindergarten program in Tulsa indicates that children who attended pre-K were advanced on pre-reading skills by 9 months, pre-writing skills by 7 months, and pre-math skills by 5 months, compared to similar children who did not participate. The Tulsa study also found more modest gains in social-emotional development, including higher attentiveness and lower timidity (but not differences in other aspects of problem behavior). Likewise, a recent study of Boston's city-wide prekindergarten program found moderate to large effects on children's language, literacy, numeracy, and math skills, and smaller impacts on children's executive functioning and emotion recognition. In Tennessee's pre-K program, participating children scored about one-third of a standard deviation higher on cognitive tests than non-participants at the end of the pre-K year. Further, research indicates that Head Start participation is associated with increased receipt of health screenings, immunizations, and dental exams, and a small decrease in body mass index (BMI) over the course of the academic year (full-day programs were found to contribute to larger reductions in obesity than half-day programs, by about 4 percentage points). The recent Head Start Impact Study (HSIS) found small to modest benefits for school readiness skills (e.g., language, cognition) and social-emotional skills (e.g., hyperactive and withdrawn behaviors for the 3-year-old cohort only) at the end of the Head Start year, although by 1st and 3rd grade, these impacts were mixed or mostly diminished.