Since 1990, the Milwaukee Parental Choice Program (MPCP) has enabled low and middle-income parents to attend private Milwaukee schools at state expense. In 2010, the Wisconsin Department of Public Instruction released, for the first time, results of newly required state standardized tests for students using the MPCP. This article uses an original data set from Milwaukee's two-decade-old private school voucher program to test several hypotheses on the impact of the first public release of test scores on school enrollment patterns. Specifically, the article uses quantitative methods to test (a) whether enrollment decreased at lower performing schools, (b) whether low-performing schools were more likely to close compared with higher performing schools, and (c) whether historical school-level growth patterns were significantly different after the release of test scores. The article finds that enrollment increases at higher performing schools were larger than at low-performing schools. However, the link between test scores and enrollment patterns disappears after controlling for available school-level characteristics. The analysis provides a first peek at how a transparency intervention affects enrollment patterns in an education marketplace.