Do charter schools improve their students' test scores and later life outcomes? This can be a tough question to answer because even when charter school students succeed, it's not always clear that the charter school is what's responsible. Most researchers have studied results from charter school admissions lotteries, but critics worry that these studies don't tell us anything about how the vast number of students who don't wind up in admission lotteries would do in charter schools. In a study appearing in the July issue of the American Economic Review, authors Atila Abdulkadiroğlu, Joshua Angrist, Peter Hull, and Parag Pathak develop a new approach that can tell us more about how different kinds of students respond to charter education.