Inter-species discourse, visuality and representations of human-animal co-embodiment were closely associated with horsemen throughout the seventeenth and eighteenth centuries, and these becomings were frequently described as the ideal state of being, an essential state of being, for a solid, balanced and prosperous nation. In this thesis I explore how the presence of an animal, interactions with it and human-animal performance as a horseman, were embodied and used by men in constructing, visualizing and destabilizing, or solidifying, masculinities. Masculinities that were at once influenced by changes in normative gender codes, but which were also tied to the longer tradition of honourable and militaristic human-animal communication. I argue it was through the visible and material presence of horses that many men worked to establish themselves as elite members of a close community of fellow horsemen and of society at large. Horses were the mediators through which men were viewed, reviewed and understood, and through which their public reputations as masculine horsemen were established. Formed off OUT core chapters, th is thesis focuses on key horsemen from the seventeenth and eighteenth centuries. It first explores the associated political discourses and modes of centauric disp lay used by William Cavendish, the first Duke of Newcastle, in the seventeenth century, and the many practitioners (male and female) of Mr. Carter's, Philip Sidney's and Domenico Angelo's riding Academies in the early eighteenth. It also investigates the analogous but unique horsemanship and horses of Astley's Amphitheatre, and the politicized equestrian caricatures of Henry William Sunbury at the end of the century. This 'snapshot' approach allows for the inclusion of the nonhuman into the study of masculinity, and for new understandings of how men understood themselves as men; how they performed their gender, status and political beliefs; and how central horses were to the lived realities of socially elite men.