Michael J. Petrilli David Griffith:

High-quality studies continue to find that urban charter schools boost achievement by more than their traditional-public-school counterparts—an advantage that has only grown larger as the charter sector has expanded and matured. For example, a 2015 analysis of charter performance in forty-one urban locations, conducted by the Center for Research on Education Outcomes (CREDO), estimated that students who attended charter schools in these cities gained an average of twenty-eight days of learning in English language arts (ELA) and forty days of learning in math per year. Students who enrolled in urban charters for at least four years gained a total of seventy-two days of learning in ELA and 108 days—over half a year’s worth of learning—in math. Moreover, the gains were even larger for Black and Latino students, and the performance of the charter sector improved dramatically over the course of the study period (i.e., between the 2008–09 and 2011–12 school years).

Understandably, some were skeptical of these results. Yet evaluations of matching approaches such as CREDO’s suggest that its estimates closely resemblethose generated by a random lottery, meaning they aren’t the product of “selection bias” or unobserved differences between students in charter and traditional public schools. Nor, according to multiple studies, is there much evidence that charter schools cream the best students. (Indeed, some research suggests that charters enroll unusually low-performing students.)

Emerging research also suggests that the gains associated with charter school attendance go far beyond test scores. For example, recent studies have also found a positive relationship between enrollment in urban charter schools and long-term, real-world outcomes, including college enrollment, teenage pregnancy, incarceration, and voting.