This report collects the results of all available empirical studies using the best available scientific methods to measure how school vouchers affect academic outcomes for participants, and all available studies on how vouchers affect outcomes in public schools. Contrary to the widespread claim that vouchers do not benefit participants and hurt public schools, the empirical evidence consistently shows that vouchers improve outcomes for both participants and public schools. In addition to helping the participants by giving them more options, there are a variety of explanations for why vouchers might improve public schools as well. The most important is that competition from vouchers introduces healthy incentives for public schools to improve.