“Concubinaries” begins the work of defining the concubinal union and delineating its variegations. It first delineates three distinct varieties of concubinage—elite, domestic, and lower class—and provides nuance to make plainer the overlapping boundaries between these categories. In addition, this chapter further textures our understanding of concubinaries and the concubinal union through a discussion of the defining features of the relationship. As many various forms as the concubinal relationship could have taken as it played out on the ground, most arrangements involved relative stability, financial support, some level of exclusivity, and a recognition of the union by the community as demonstrated through the language they used to describe it. Finally, the chapter describes the concubinaries themselves, addressing particularly class, status, and national origin. Though it makes some generalizations about the people involved in concubinal relationships, but for the most part, the chapter demonstrate the extraordinary variety of people who might at some point in their lives take up such a relationship. This chapter also advances an argument about the immense variety and flexibility of concubinage, describing a union useful at all levels of society.