Abstract: The concept of representation plays an important role in Marsilius of Padua’s major work, the Defensor Pacis. Yet, with a few notable exceptions,Marsilius’ concept of representation has received relatively little attention among recent scholars. The main purpose of this article is to fill this gap and scrutinizeMarsilius’ concept of representation as an autonomous theoretical and political problem in the Defensor Pacis. The paper first surveys the different meanings of repraesentatio that appear in Marsilius’ 1324 work. It then identifies an understanding of political representation — repraesentatio identitatis — that unites most cases in which Marsilius explicitly deploys a political language of representation, whether in the context of secular or church governance. Marsilius’ usage of the concept of repraesentatio identitatis is particularly innovative as it turns a notion coming from corporate theory in civil and canon law into a specifically philosophical-political theory.