This first paper in the series concentrates on school context and outlines a framework which identifies and relates a variety of factors that influence differences in policy enactments between similar schools. In taking context seriously in our four case-study schools we argue that policies are intimately shaped and influenced by school-specific factors, even though in much central policy making, these sorts of constraints, pressures and enablers of policy enactments tend to be neglected. This paper considers aspects such as school intake, history, staffing, school ethos and culture, "material" elements like buildings, resources and budgets, as well as external environments. These factors are conceptualised as situated, material, professional and external dimensions and we aim to present a grounded exploration of the localised nature of policy actions that is more "real" and realistic than that often assumed by policy making. (Contains 3 notes.)