Understanding the gaps in school readiness that exist among America’s children when they begin kindergarten is critical, especially as we expect the majority of our children to complete high school ready to enter college or begin a career and to assume their civic responsibilities. Achieving these societal goals requires strong math, reading, science, and other cognitive skills, as well as noncognitive skills such as the abilities to work well and communicate effectively, solve problems creatively, and complete tasks. Unfortunately, the weak early starts that many of our children are getting make it hard to attain these goals. Since key foundations for learning are established beginning at birth, starting school behind makes it likely that early disadvantages will persist as children progress through school and last into their adult lives.

As the figure above shows, the most socioeconomically disadvantaged children lag substantially in reading skills as early as kindergarten. This skill level rises along with social class. For example, children in the highest socioeconomic group (the high SES fifth) have reading scores that are significantly higher—by a full standard deviation—than scores of their peers in the lowest socioeconomic group. To put this in perspective, we would need four “substantively important interventions” (defined by the What Works Clearing House as those that have an effect-size of a quarter of a standard deviation or greater) to close such a disparity.

Social-class gaps are also found in other skills that are important for students’ development and for school success—for example, social skills, creativity, and self-control. To prepare children for kindergarten and to address the link between inequality and education that is evident in our analyses, there is a critical need not only to expand access to and quality of early education programs, but also to rethink our social and economic policies more broadly.