This chapter considers issues of policy implementation – the work that is done to move from policy to practice so that policies take the desired form and have the desired results. Research on implementation goes back more than thirty years, with many tracing its origins to work on the implementation of US federal government anti-poverty programs in the 1960s (Pressman and Wildavsky, 1973). Since then, a large body of research has accumulated in education and other policy fields, with the general finding that moving from policy to practice is a very uncertain business. A whole series of difficulties – some of them generic to policy implementation and others particular to schools – stand in the way of policies being put in place as intended (McLaughlin, 1987). Although the problems of implementation are well known, governments have tended to give relatively short shrift to these issues in the policy process.