We analyse the initial impact of a major school admission reform in Brighton and Hove. The new system incorporated a lottery for oversubscribed places and new catchment areas. We examine the post-reform changes in school composition. We locate the major winners and losers in terms of the quality of school attended. We match similar cities and conduct a difference-in-difference analysis of the policy change. The results are complex: we see an increase in student sorting but we also see a significant weakening of the dependence of school attended on student’s prior attainment.