Starting Early: Introducing the Issue

Across the nation, more and more people want to see children receive quality education before kindergarten. Public opinion polls suggest that 70 percent of adults favor such programs, partly because of the irresistible idea that “starting early,” and ensuring that children arrive in school ready to learn, is the best way to generate happy, healthy, and productive adults.¹ The notion of starting early resonates. Head Start, the federally funded prekindergarten program for children from low-income homes, was a cornerstone of President Lyndon Johnson’s War on Poverty. Even then it was believed that students can’t fully benefit from an elementary education if they don’t arrive at kindergarten ready to learn. Presidents with views as disparate as those of George W. Bush and Barack Obama have called for strengthening early childhood education in their budgets and State of the Union addresses.

One reason for the strong support of early childhood education is the seemingly compelling evidence that exposing children to educational experiences when they’re young can have profound effects on later educational, social, and adult outcomes. In fact, as Lynn Karoly points out in this issue, estimates based on some older pre-K programs suggest that every dollar invested in prekindergarten pays off $3 to $17 in terms of benefits, both to the adult individual and to society. That suggests prekindergarten is one of the most effective investments that we can make in children. Indeed, James Heckman of the University of Chicago, a Nobel laureate in economics, has argued that investments made in early childhood are more beneficial and also more cost-effective than those made in later childhood and adolescence.²

The idea that prekindergarten can enhance later learning and adult success is based on the premise that if pre-K programs provide enriching activities more intensively and more intentionally than parents can, then those programs have the potential to boost children’s learning and skill acquisition. In brief, quality pre-K experiences can teach children the skills that make it easier for them to learn new skills in early elementary school: that is, skills beget skills.

Differences in literacy and cognitive skills between children in low-income families and their better-off counterparts are already apparent by age three, or perhaps even earlier.³ The pre-K education programs initiated in the 1960s and 1970s were designed to reduce those gaps by providing quality pre-K education to disadvantaged children, who were less likely to be ready for school. Few pre-K programs existed in the low-income neighborhoods where most disadvantaged children lived, and parents with little income and education were therefore less likely to send their children to prekindergarten than were parents with more resources. And when disadvantaged parents were able to find a pre-K program, it was likely to be of relatively low quality.⁴

Based on these observations, we would expect that children from disadvantaged environments would benefit the most from pre-K education; that high-quality programs would deliver the greatest benefits; and that children who received such education would benefit more than those who remained at home, cared for by parents, family, and friends. Comparisons between different pre-K programs, on the other hand, shouldn’t show such a stark contrast. These assumptions imply that not all programs would show equal benefits in empirical evaluations. Scholars have called this heterogeneity in outcomes. Interpreting the research requires attention to many factors—family background, comparison group composition, and programs’ quality and intensity.

Scholars have extensively studied the efficacy of pre-K programs, especially those offered to four-year-olds. Of more than 100 evaluations of pre-K programs, the vast majority used random assignment of children to receive the preschool treatment or not.⁵ Most of these experimental programs served children from low-resource families, in keeping with the premise that these children were less likely to have the skills needed for kindergarten and were therefore most likely to benefit. Consequently, we know the most about how preschool influences children from disadvantaged backgrounds. And because many of these...