Résumé : The notion of “transnationalism” emerged in the 1970s, in the field of international relations, to describe the modalities of non-state actions — and their spatialities — within the framework of “world politics.” The point was to break with the state-centred perspective of political developments to include non-state actors in a complex political game that no longer takes place exclusively within the legal and physical borders of nation-states. Thus, new approaches to transnational relations began to explore, within and beyond the state, the processes, networks and practices of multiple social actors that unfold according to specific modalities and scales: businesses, diasporas, religious communities, scientific or cultural networks, trade unions, social movements (including global protest movements), non-governmental organisations, etc. Gradually, and in a diffuse way, the concept came to not only refer to the individual and collective practices and strategies of persons, consumers, migrants, and professionals of a given field, but also to the culture of formal or informal institutions that operate transnationally.