Charter schools are among the most controversial issues in education today, with much of the debate focused on whether they produce better testing results than comparable regular public schools. Too often, these discussions either rely on a tiny handful of studies, or on raw, cross-sectional testing results, which are not valid measures of school effects.
This policy brief provides an accessible review of the research on charter schools’ testing effects, how their varying impacts might be explained and what this evidence suggests about the ongoing proliferation of these schools.
The public debate about the success and expansion of charter schools often seems to gravitate toward a tiny handful of empirical studies, when there is, in fact, a relatively well-developed literature focused on whether these schools generate larger testing gains among their students relative to their counterparts in comparable regular public schools. This brief reviews this body of evidence, with a focus on high-quality state- and district-level analyses that address, directly or indirectly, three questions:
- Do charter schools produce larger testing gains overall?
- What policies and practices seem to be associated with better performance?
- Can charter schools expand successfully within the same location?
The available research suggests that charter schools’ effects on test score gains vary by location, school/student characteristics and other factors. When there are differences, they tend to be modest. There is tentative evidence suggesting that high-performing charter schools share certain key features, especially private donations, large expansions of school time, tutoring programs and strong discipline policies. Finally, while there may be a role for state/local policies in ensuring quality as charters proliferate, scaling up proven approaches is constrained by the lack of adequate funding, and the few places where charter sectors as a whole have been shown to get very strong results seem to be those in which their presence is more limited. Overall, after more than 20 years of proliferation, charter schools face the same challenges as regular public schools in boosting student achievement, and future research should continue to focus on identifying the policies, practices and other characteristics that help explain the wide variation in their results.