The iconic image of the knight on horseback represents just one facet of the horse’s imprint on legal, political, and social systems developing in medieval Iberian society. This chapter argues that historical and bodily relations with horses shaped the negotiation of social status and the administration of territory during the dynamic periods of peace, conflict, and negotiation among Iberian kingdoms in the tenth to fifteenth centuries. Defining the set of practices, ideals, and institutional hierarchies making up an Iberian "culture of the horse” brings to light a fundamental tension in which the horse served as both an agent of control and a means to disrupt power relations.