The marriage in 1490 of Francesco Gonzaga, Marquis of Mantua, and Isabella d’Este, daughter of the Duke of Ferrara, cemented an important Italian dynastic alliance and was in no sense a love match. Francesco and Isabella were well aware, however, that they had to establish a harmonious conjugal rapport if the strategic aims of their union were to be realized. This study examines the ways in which the Este-Gonzaga couple built familiarity, affection, and shared interests through frequent letter exchanges that both shaped and facilitated their domestic and political collaboration. The epistolary evidence provides new insights into how an aristocratic Renaissance marriage was experienced by the couple themselves and about the means by which a relationship that was exposed to the full force of contemporary politics, with all its conflicts of dynastic loyalty, was sustained through dialogue and negotiation.