This chapter examines the ambiguity of leaks and, in doing so, it addresses under-debated aspects of secrecy and transparency in the European Union. Research on leaks as a distinct phenomenon in the EU is only beginning to emerge as part of a broader growing scholarship focused on issues of European secrecy. As we map the actors and regulatory framework of official secrets and how they are protected at the EU level, we hope to contribute towards a better comprehension of the reasons for leaks and how they happen in the EU. Leaks can bring information into the public domain that was not public before and encourage public discourse (more de facto transparency). At the same time, leaks can induce counter-reactions in the form of new rules or additional policing that discourage both unauthorised disclosure but also proactive legal disclosure (more de jure secrecy). We address these tensions over leaks, focusing on the Commission and the Council. On the basis of the legal and empirical analysis, the chapter offers a broader discussion of the state of secrecy in the EU and points to the main issues that require future research.