This paper examines the impact of the Indiana Choice Scholarship Program on student achievement for low‐income students in upper elementary and middle school who used a voucher to transfer from public to private schools during the first four years of the program. We analyzed student‐level longitudinal data from public and private schools taking the same statewide standardized assessment. Overall, voucher students experienced an average achievement loss of 0.15 SDs in mathematics during their first year of attending a private school compared with matched students who remained in a public school. This loss persisted regardless of the length of time spent in a private school. In English/Language Arts, we did not observe statistically meaningful effects. Although school vouchers aim to provide greater educational opportunities for students, the goal of improving the academic performance of low‐income students who use a voucher to move to a private school has not yet been realized in Indiana.