The representatives of contested states – that is, territories whose claim to sovereign statehood is not, or is not fully, recognised by the international society of states – often make significant efforts to engage in diplomacy. Two literatures have recently begun to explore these diplomatic activities, one focusing on the ‘rebel diplomacy’ of insurgents and secessionist movements, the other on ‘liminal actors’ in global politics. However, these two literatures have defined the phenomenon in very different ways, namely, as either instrumental action or cultural performance, and study it largely without regard to each other's insights. My argument in this article is that contested state diplomacy can be better understood if we appreciate the nature of modern diplomacy as a set of bureaucratic practices. As a routinised process within a bureaucratic organisation, modern diplomacy both gives rise to specific decisions and sustains the reality of the state as the locus of legitimate power. The representatives of contested states therefore have strong reasons to set up more or less rudimentary bureaucracies for their diplomacy. I use the history of Kosovo's foreign policy institutions as a paradigmatic case to demonstrate how everyday bureaucratic practices fuse instrumental action and cultural performance and further theorise the interplay of ‘political’ and ‘technical’ conduct in contested state diplomacy.