While studies consistently find that ECE participation has positive impacts on children's outcomes at program's end, only a few have longitudinal data available to assess long-term outcomes.
In general, differences attributable to program participation on measures of achievement diminish or disappear during elementary and secondary schooling. However, despite the convergence of scores on measures of academic achievement, multiple studies show long-term effects on important life outcomes in late adolescence or early adulthood. For example, children who attend Head Start have higher rates of high school completion, college attendance, and employment, as well as decreases in behavior problems, grade retention, and criminal activity, when compared to similar children who did not attend Head Start. Overall, Head Start attendance results in an increase of nearly one-quarter of a standard deviation (.23 SD) across an index of outcomes, equivalent to about one-third of the gap between Head Start participants and other children that existed prior to participation. The projected gains in earnings associated with program attendance more than offset the costs of the program, resulting in a positive benefit/cost ratio for Head Start. Head Start may also show long-term impacts on health outcomes, particularly large reductions in obesity and on the likelihood of smoking.
Because documenting long-term impacts require longitudinal studies and measures taken decades after participation, to date, we lack information on the long-term impacts of public pre-K programs. A small number of model, intensive ECE programs with available longitudinal data demonstrate large long-term impacts. For example, evaluations of two well-known ECE programs, the Perry Preschool and the Carolina Abecedarian projects, show very large initial impacts on educational achievement, and very large effects on schooling and earnings during adulthood. Likewise, the Chicago Child-Parent Centers study also shows substantial short-term effects on educational achievement, plus long-term reductions in crime and substance abuse and long-term improvements in high school graduation rates and adult earnings.