Notwithstanding its relevance, social mobility has not been at the forefront of the agenda for historians of the Middle Ages. The first part of this paper deals with the reasons for this lack of interest, highlighting the role of historical models such as the French ‘feudal revolution’, the neo-Malthusian interpretations, the English commercialisation model and the great narrative of Italian medieval merchants. The second part assesses the extent to which this lack of interest has been challenged by conceptions of social space and social mobility developed in recent decades by sociologists and anthropologists. Therefore, it is really important to indicate the gaps in our understanding, and to clarify research questions, technical problems and methods. The paper examines the constitutive elements of social identities, the plurality of social ladders, and the channels of social mobility. It touches upon the performative role of learned representations, and upon the constraints imposed upon human agency by family practices and genre. It underlines the importance of studying the mobility inside social groups, and argues that we must distinguish between two different types of medieval social mobility: autogenous social mobility, and endogenous or conflictual social mobility.