The peace treaties following the Great War dictated that certain nation-states accept, as the price of international recognition, agreements to protect the rights of their minority populations. Responsibility to 'guarantee' and 'supervise' the minority treaties fell to a novel and untried international institution, the League of Nations. It established the 'minority petition procedure', an unprecedented innovation within international relations that initiated transnational claims-making. Focusing on the supervision of agreements pertaining to the Macedonian region, I examine how the Minorities Section of the League of Nations Secretariat handled 'minority petitions' alleging state infractions of minority treaties. I consider, in particular, a preoccupation among both bureaucrats and states with 'violent language' in petitions. I argue that this preoccupation signalled anxieties about honour, sovereignty and legitimacy, about the ambiguous position of 'minority states' and about the potentially explosive effects of popular energies in the post-war international order.