Drawing on an extensive literature review, this chapter traces the main directions in the research on policy implementation in the EU, illustrating how and from which perspectives the process of policy change has been analysed. Particular attention is paid to how the dimension of policy discourse and its linkage with policy programmes and instruments has been dealt with by the literature. Evidence is provided that a number of gaps still exist in our knowledge of the policy process in the EU, especially with regard to the effectiveness and impacts of its policy instruments that have largely been built on the expectation about major advantages of new flexible forms of governance, relying on learning, persuasion, standardisation of knowledge about policies, iterative processes of monitoring and target readjustment. By elaborating on the concept of usage, an actor-centred analytical framework is developed in order to appraise the implementation dynamics of selected EU policy programmes underpinned by the sustainable development mainstreaming approach.