This chapter endeavours to respond to Fishman’s appeal for ideological clarification by focusing on the often-neglected role of supranational actors (including an analysis of their own constitutive actors and processes) in shaping, diffusing, and mediating policy ideas and discourse on linguistic diversity and multilingualism. It identifies the main types of actors at the level of global governance with regard the UN System. It outlines their respective contributions in terms of ideas, and their functions in terms of processes, focusing on the interactions of these actors. In so doing, it analyses UN discourse in the early twenty-first century (where discourse is understood as language as meaningful social action) concerning multilingualism and linguistic diversity, produced through various media and in various contexts. These include: normative texts (especially in the field of human rights), position papers, reports, policy recommendations, action plans, methodological guidelines, and internet materials.