In the spring of 1998, Parents Advancing Choice in Education (PACE), a privately funded non-profit corporation, offered low-income parents within the Dayton metropolitan area an opportunity to apply for a scholarship to help defray the costs of sending their child to private schools in Dayton and other parts of Montgomery County, Ohio. All students from low-income families entering a grade between kindergarten and twelfth grade were eligible. PACE offered scholarships to 515 students who were in public schools at the time and 250 students who were already enrolled in private schools. This evaluation examines the program's impact after two years on those students in grades 2-9 who had been attending public schools prior to receiving a scholarship. PACE distributed scholarships among applicants by lottery, thereby making it possible to conduct an evaluation as a randomized experiment. All students who applied for the program and attended second-year follow-up sessions completed the Iowa Test of Basic Skills in reading and mathematics. Parents were invited to respond to a questionnaire about their experiences with their school, as were students in grades 4-9. By comparing student test scores and the questionnaire responses of families who received a scholarship with those who entered the lottery but did not receive a scholarship, we are able to estimate the effects of the offer of a voucher, as well as the effect of actually attending a private school. Similar randomized field trials of school voucher interventions are currently being conducted in New York City and Washington, DC.