Thirty Years of Charter Schools: What Does Lottery-Based Research Tell Us?

Charter schools are highly debated in policy and political discussions about delivering public education. As “laboratories of innovation” that often use lotteries to assign spots, they hold the potential to generate rigorous evidence about effective educational practices. This paper synthesizes and summarizes findings from charter lottery studies and identifies priority areas for future lottery-based research. Existing evidence shows that charter schools can improve academic achievement and longer-term outcomes like four-year college enrollment, particularly among lower-performing students, non-white students, low-income students, and students with disabilities. However, these findings are limited to oversubscribed schools and primarily come from studies that take place in large urban areas in a few states. Future lottery-based charter school research should expand the geographic coverage of existing studies, update the evidence on K-12 academic outcomes, and explore understudied areas such as non-test-score outcomes, college outcomes, and earnings. Studying these topics would bolster existing evidence and inform future education policymaking within the charter sector and beyond.