The expansion of private school choice programs has been accompanied by a growing call for regulation of those programs. Individual private schools decide whether to participate in voucher programs based on expected benefits and expected costs. An unintended consequence of attaching heavy government regulation to voucher programs is that it raises the costs of participation, which could reduce the number of private schools available to the children who need them the most. Moreover, the authors hypothesize that lower-quality schools are more likely to participate in regulated voucher programs because they are the most desperate for additional enrollment and funding. They empirically examine this hypothesis using school-level data from two of the most highly regulated voucher programs in the United States: the Milwaukee Parental Choice Program (MPCP) and the Ohio Educational Choice Scholarship Program (EdChoice). Using tuition, enrollment, and customer review scores as proxies for school quality, they find strong evidence suggesting that lower-quality private schools are more likely to participate in voucher programs in both locations. This result is a big problem if their aim is to provide high-quality educational options for children who are currently in government schools.