This article develops an ‘economy of secrecy’ as a framework to understand how secrecy regulates interstate relations and to explicate why states react differently to breaches of secrecy. Drawing upon Simmel, the article argues that secrecy shapes interstate relations by tuning the ratio of ‘knowledge’ and ‘ignorance’. Furthermore, while the economy of secrecy acknowledges the existence of many types of secret, it emphasises their common underlying mechanisms, namely: secrecy as a field of power, secrecy as a field of performance, and secrecy as a normative terrain. Finally, the economy of secrecy is agnostic with regard to the moral character of promoting secrecy. In order to substantiate the argument, the article examines three recent iterations of how secrecy has disrupted EU‒US relations: extraordinary renditions, WikiLeaks, and Snowden’s revelations. In addition to showcasing how the economy of secrecy operates, these examples contribute to our understanding of how secrecy affects information flow and dissemination in world politics.