This essay examines the conceptual relationship between marriage and friendship in the four-book dialogue on the family composed by the Florentine humanist Leon Battista Alberti during the 1430s. Alberti’s interlocutors argue variously that marriage is a burden, a procreative engine, a site of companionship, an economic partnership and, remarkably, the locus of true friendship. Their discussion provokes a rethinking of these two interpersonal bonds, which emerge not only as critical to the stability of the family, the state and society, but also as a vital means of pressing erotic love into the service of the family through conjugal friendship.