Little is known about the supply side of voucher programs, despite schools' central role in program effectiveness. Using survey and interview data on the Indiana Choice Scholarship Program (ICSP), I analyze schools' participation decisions and early implementation experiences to understand better how schools respond to program regulations. I find that schools choosing to participate in the ICSP were most concerned with how their academic and religious identity would be affected, whereas those choosing not to participate were most concerned with the program's procedural requirements. Participating schools did experience early changes to the academic and religious composition of their student bodies as well as challenges related to the program's administrative requirements.