Despite the principle of equality among states, in any multilateral context, some participants have much greater influence than others. The practice of diplomacy is indeed organised along a hierarchy of influence that is largely tacit but nevertheless quite real in its effects. Delegates play specific roles, related to different ways of doing things, privileges and responsibilities. How does this international hierarchical order function in daily practice? What are the social rationales whereby ranks and roles are distributed around the multilateral table? Based on the political sociologies of Pierre Bourdieu and Erving Goffman, this research project focuses on the practical rationales of multilateral diplomacy. In an initial stage, formal analysis enables us to better grasp the relational rationales of the practice of permanent delegations to international organisations. Then, the research focuses on specific sites for diplomatic interactions in order to understand their local sources of influence. Two case studies of institutional transformation have been chosen in order to contrast their differences. Firstly, throughout adaptations in the post-Cold War period, NATO has remained the perfect example of a multilateral organisation that is highly structured and regulated by an ambassadorial “sense of place”. Secondly, the reform of the United Nations Security Council has given rise to heated debated about the principles whereby a handful of privileged states are granted institutionalised advantages.