This essay aims to contribute to a better understanding of the role played by women as cultural mediators in the eighteenth century. Its starting point is the little-known figure of María, Countess of Fernán Núñez, Spanish ambassadress to Portugal (1777–87) and France (1787–91), who led a transnational life marked by travel, international courts, and embassies—all spaces of sociability traditionally linked to the study of cultural mediation, an area that in recent years has begun to be considered in relation to gender. The Countess's experience sheds light on the contributions made by diplomats' spouses to the political and cultural life of Europe and on the ways in which a wife and husband could work as a team. Methodologically, this case study also provides an opportunity for reflecting on the sources with which we can reconstruct the cultural mediation carried out by women, who tend to be far less visible in official records.