The complex relation between educational policies as laid down by the State and the effects of these policies in practice has been a challenge for educational research for some time. Even finding out the purposes and intentions of a given policy in itself is quite a difficult task, since policies are the result of negotiations between different agents that participate in the formulation process, and the final product is often not necessarily a coherent and univocal one. Furthermore, policies are not transmitted into a vacuum. There are social, institutional and personal circumstances affecting the way in which policies are understood by those who (are supposed to) put them into practice.