Washington, DC has nearly half of its public school student body enrolled in charter schools, each of which has had its own admissions process and lottery for oversubscribed schools. The other half attend the one traditional district: DC Public Schools, which has an “out-of-boundary” enrollment option for parents to transfer to a district school outside their neighborhood if space permits, with its own lottery for oversubscribed schools. To help this school choice market clear more efficiently for parents and schools, the city’s Deputy Mayor for Education instituted a common application lottery in 2014 to unify the process of selecting into one of any DC public school and the majority of DC charter schools. We use applicants' rank-ordered school preferences and publicly available information on individual schools to study the school choice market in DC. We first describe the availability and demand for spaces across schools under DC's school choice process. A discrete choice model is then used to quantify parents' relative valuations of school attributes related to academics--such as achievement levels, school value added, and teacher effectiveness--and less academic attributes of schools, including student body demographics, the incidence of crime near a school, and commuting distances calculated from home and school address data. The resulting choice parameters allow us to simulate changes in school compositions over time and how these compositional drifts would respond to increased capacity for school choice and changing choice sets.