ABSTRACT This article proposes an innovative approach to early modern representative institutions, from the later fifteenth century to the early eighteenth. It argues that only a transnational, interdisciplinary, and comparative study of such bodies can reveal their shared culture and prominence in contemporary political discourse, public memory, and cultural production. Central to this new approach is the concept of ‘parliamentary culture’, which sees representative assemblies as collective constructs and embodiments of a political community, and encompasses the transnational tradition of customs, ideas, and cultural expressions associated with them. The article aims to: (1) sketch out the institutional, geopolitical, and historical scope of our enquiry; (2) define parliamentary culture as a collection of practices of legitimation, negotiation, and debate in political assembly that are central to the life of a community; and (3) demonstrate that the distinctive institutional cultures of representative assemblies were an essential component of the public life and political thought of early modern countries; and that there was a common culture of representative assembly shared and recognized throughout Europe which was variously transplanted to and adapted in the overseas territories of the Iberian, Anglo-British, and Dutch empires, often through interaction with Indigenous traditions of assembly. The underlying argument is that only by looking at early modern representative bodies in this way can we appreciate the vitality and significance of this type of political organization.