Permanent Structured Cooperation (PESCO) is a major initiative in differentiated integration within the EU in the field of defence. This paper assesses whether the legal framework (the 20 binding commitments), and the way the 25 participating member states have organised to implement it, are sufficient to achieve the purpose of PESCO. Moreover, it asks the question whether there is a clear sense of purpose at all. Analysing the ongoing debates between the member states about the future of the Common Security and Defence Policy as a whole, the paper then proposes recommendations to make PESCO work: by focusing on a more concrete objective, by prioritising strategically relevant projects and by enhancing compliance.