Europe’s deteriorating security environment is reinvigorating EU defence cooperation. Key to credible cooperation in this area is Permanent Structured Cooperation (PESCO), which the EU launched in 2017 to enhance joint capability development and operational readiness. To assess whether the initiative is delivering on its objectives, this policy brief analyses the origins, legal framework, functioning, third-country participation and overall performance of all 83 PESCO projects to date across 26 member states. PESCO still faces significant institutional hurdles to reach its full potential as the EU’s core platform for focused, scalable defence cooperation and enhanced third-country participation. The brief concludes with recommendations for targeted, pragmatic reforms.