Traditional conceptions of family life in Renaissance Italy have emphasized the importance of male kinship connections and associations. Yet the correspondence found between sisters and brothers in the Spinelli family, a prominent merchant family in sixteenth-centuryFlorence, reveals instead how both women and men viewed family identity as moving beyond lineage considerations. This article examines two case studies of brother-sister interactions in the Spinelli family to suggest how alternative configurations of family life at times worked with and at other times challenged paternal power and patriarchal authority. The article aims to deconstruct notions of patriarchy in order to reveal the multiple constructions and articulations of power in Florentine households and communities in the sixteenth century. The case of the Spinelli suggests that the dominant patriarchal model did not always reflect the functioning of family life, gender relations, social connections, and economic affairs found in early modern Europe.