In most of the U.S., the process for assigning children to public schools is straightforward: take a student's home address, determine which school serves that address, and assign the student accordingly. However, states and cities are increasingly providing families with school choices. A key question facing policymakers is exactly how to place students in schools in the absence of residential school assignment. In the immediate aftermath of Hurricane Katrina, New Orleans families could choose from an assortment of charter, magnet, and traditional public schools. The city initially took a decentralized approach to choice, letting families submit an application to each school individually and allowing schools to manage their own enrollment processes. This approach proved burdensome for parents, who had to navigate multiple application deadlines, forms, and requirements. Moreover, the system lacked a mechanism for efficiently matching students to schools and ensuring fair and transparent enrollment practices. Today, New Orleans families can apply to 89 percent of the city's public schools by ranking their preferred schools on a single application known as the OneApp. The city no longer assigns a default school based on students' home addresses. Instead, a computer algorithm matches students to schools based on families' ranked requests, schools' admission priorities, and seat availability. Experience with the OneApp in New Orleans reveals both the significant promise of centralized enrollment and the complications in designing a system that is technically sound but clear to the public, and fair to families but acceptable to schools. The approach remains novel, and some New Orleanians have misunderstood or distrusted the choice process. The Louisiana Recovery School District (RSD) set three goals for the OneApp: efficiency, fairness, and transparency. This article considers the OneApp and centralized enrollment in the context of these goals, at times defining them differently from how the RSD defines them. This article examines not just the technical process of assigning students to schools, but also the relationship with the city's broader school­-choice setting, since the OneApp is so intertwined with New Orleans' overall education policy. Researchers used data from interviews with 21 parents and surveys of 504 parents about the OneApp and school choice that were conducted in the spring of 2014 by the Center on Reinventing Public Education (CRPE), and utilized de-­identified OneApp data containing families' school requests and assignments for the 2013-14 school year. RSD administrators routinely consider the system's successes and failures, and modify it accordingly for the next iteration, all while the public continues to acclimate and learns how to better leverage the choice system. Continued learning and adaptation will be essential to the OneApp's sustained success and the ability of New Orleans to provide the country with a model for student enrollment that is worthy of replication elsewhere.