Since 2005, the English government has adopted a policy of regenerating disadvantaged neighbourhoods by reconstructing them as mixed communities, in which schools appealing to higher income residents are a key feature. This creates some difficulties for those concerned with social justice, who support the notion of integrated schools and neighbourhoods, but are concerned that the re-modelling of neighbourhoods and schools in this way could further disadvantage existing populations. Mix is supported but mixing is opposed. This article interrogates this "social justice dilemma" by analysing the origins and development of the mixed communities policy. It demonstrates the distinction between the principle of mix and the policy of mixed communities, while illuminating the political and discursive processes that conflate the two. Finally the authors indicate how research can be mobilised in support of neoliberal discourses about neighbourhoods and schools and draw some broader conclusions for education research and policy. (Contains 1 figure and 4 notes.)