How are international phenomenon rendered knowable? By which means and practical devices is international knowledge generated? In this article I draw on the case of contemporary maritime piracy to introduce a research framework that allows addressing these questions. Arguing that the practices of international knowledge generation are weakly understood I show how concepts from science and technology studies provide us with the tools to study these practices empirically. Relying on the practice theory of Karin Knorr Cetina, I introduce the concepts of epistemic infrastructures, epistemic practice, and laboratories and demonstrate how they spur interesting insights on knowledge generation. I investigate three ‘archetypes’ of epistemic practices in detail and show how these generate knowledge about piracy for the United Nations: the quantification practices of the International Maritime Organization, the interpretation work of a Monitoring Group and the net-work of a Special Adviser. The article introduces an innovative agenda for studying knowledge generation in international relations by focusing on the practical epistemic infrastructures that maintain knowledge about international phenomena.