This book aims to trace the development of a new conception of 'mobility citizenship' in Europe historically, demographically and experientially. To this aim, it adopts a 'constellationist' approach applied to the intra-European mobility space and uses the case studies of Hungarian and Romanian migration to the United Kingdom to develop a multidimensional meso-level comparative empirical analysis of mobility-citizenship constellations. The main theoretical proposition of the book is that citizenship has undergone a noticeable change in meaning and valuation, with mobility rights becoming a more central component in the structure of opportunities it provides citizens. The logic of 'mobility citizenship' is thus changing long-held perceptions around the social functions of citizenship, and consequently, the nature of contemporary transnational society. The multifaceted analysis presented in the book will appeal to readers with backgrounds in various disciplines such as political sociology, migration studies, citizenship studies, nationalism studies, or European studies.