Research is increasingly highlighting the influence of school contexts on school processes and student achievement. This article reviews a range of social justice rationales for taking school contexts into better account, and highlights the challenges contextualisation currently poses for practice and for policy. It notes important constraints on contextualised practice and limited developments in contextualising policy. There is now increasing concern to recognise and understand context in school effectiveness and school improvement research but such research needs to consider school context much more, in order to provide a stronger underpinning for contextualised policy and practice. School composition research is potentially most insightful because it addresses the issue most directly. Nevertheless future large-scale studies in this area need to overcome a number of limitations within the existing literature.