Executive Summary: "Does Prekindergarten Improve School Preparation and Performance?" by Katherine A. Magnuson, Christopher Ruhm, and Jane Waldfogel

The share of U.S. children attending early education programs has risen dramatically in recent years, but disadvantaged children remain consistently less likely to attend. Today, children whose mothers did not complete high school are half as likely to be in center-based care arrangements as those whose mothers are college educated and a similar gap exists between children from low and high-income families.

Concerns that many disadvantaged children are insufficiently prepared to start school have motivated expansions in public funding, including funding for prekindergarten -- early education programs sponsored by school districts. Since 1990, state funding for prekindergarten has increased 250% to approximately $1.9 billion, and now one in seven four-year olds are enrolled in prekindergarten.

Evidence on how prekindergarten affects school readiness and subsequent educational performance is limited. We know that model early education programs promote academic skills but know much less about typical programs, with data particularly lacking for prekindergarten. This paper begins to fill this gap by addressing three specific questions. First, does prekindergarten increase school readiness at kindergarten entry? Second, do the effects persist over time or quickly dissipate? Third, do the results differ for children with disadvantaged family backgrounds?

We use data from the newly available Early Childhood Longitudinal Study--Kindergarten Class of 1998-99 (ECLS-K), a large nationally representative sample of children entering kindergarten in the fall of 1998. The ECLS-K collects information on school performance and a rich array of family background, school, early education and child care experiences. We assess school readiness using data on academic skills and classroom behavior from the fall of kindergarten, and the persistence of effects with corresponding information from the spring of first grade.

A significant challenge is to adequately control for differential selection into early education. For example, favorable selection, whereby parents whose children attend prekindergarten possess characteristics that promote high levels of school performance, would result in a spurious positive correlation between preschool and later academic outcomes. Our primary econometric strategy is to use the detailed information available in the ELS-K to account for many potential confounding factors. We also test the robustness of our findings using fixed-effect, propensity score, and instrumental variables methods.

Our main results are as follows. 1) Prekindergarten significantly raises math and reading performance at school entry—effect sizes range from 0.10 to 0.12 in the preferred models. 2) Prekindergarten attendance increases aggression and decreases self-control—with effect sizes of 0.07-0.11. 3) Other types of center-based care have positive effects on academic outcomes and negative impacts on behavior, although these are smaller than for prekindergarten. 4) For most children, the cognitive benefits of prekindergarten quickly fade, but the behavioral effects persist. 5) However, there are more lasting cognitive gains for disadvantaged children. 6) Among children attending prekindergarten in the same public school as kindergarten, the higher reading and math skills are not accompanied by increases in behavior problems. These last findings suggest that further expansions of prekindergarten should focus on serving children from disadvantaged backgrounds and programs located in public schools.