This article introduces a collection of papers devoted to the study of secrecy in European politics across a range of EU and national settings and policy domains. Academic interest in secret politics-those aspects of public activity intentionally concealed from the public eye-and the governance of secrecy-the political processes and regulatory frameworks governing secret keeping-is growing. This interest reflects technological, social and political developments that appear to signal the end of privacy and the rapid expansion of political secrecy in European multi-level settings. As a consequence, the tensions between democratic accountability, with its transparency requirements, and political secrecy, which is typically justified on grounds of effectiveness of state action, have become more marked and more politicised. Engaging with these developments, the contributions to this collection draw on actor-and interest-centred perspectives that focus on actors' motivations in secret politics; institutional perspectives that focus on contestation over secrecy norms; and organisational perspectives that emphasise the diversity of secrecy cultures. Further research will benefit from paying special attention to a diverse range of inter-institutional and interorganisational secrecy settings; to political contestation over secrecy and the regulatory regimes that govern it; and to the refashioning of public-private secrecy architectures. KEYWORDS secrecy; transparency; privacy; european union; european politics Arguments about the justification of, and limits to, secrecy pervade European politics at both national and EU levels. For example, despite pressure by the EU on its member states to enhance transparency in the banking sector in the wake of the euro crisis, the German government and parliament are reluctant to release supervisory data relating to Germany's banks to the public (Gandrud and Hallerberg 2018). Although the European Parliament has achieved advances towards further transparency of decision making in the Council, it has largely fallen short of restricting EU governments' secrecy privileges in the Common Foreign and Security Policy (Rosén 2018). In the 'fight' against terrorism, governments have introduced targeted sanctions CONTACT Berthold rittberger