This introduction sets out the aims of the symposium on mobilities and mobilizations of the urban poor. Exploring the physical, social and imagined movements of the poor into, within and out of cities, and addressing how these movements connect to the dynamics of urban social mobilization, it argues for an incorporation of the 'mobility turn' in studies of the urban poor. The introduction proposes a number of relevant themes within this approach, starting with increased attention to the interconnections between physical and imaginative movements. This is followed by a discussion of representations of mobility and mobile representations: the ways in which physicalThis symposium explores the physical, social and imagined movements of the poor into, within and out of cities and addresses how these movements connect to the dynamics of urban social mobilization. The six articles presented here are the product of an international conference organized in September 2009 in Leiden, the Netherlands, in honor of the retiring urban anthropologist Peter J.M. Nas. The conference brought to light a number of cross-cultural insights that have been further elaborated for this symposium. The authors study the ways in which urban space is imagined and how this connects to the spatialization of the networks of the urban poor, both within and beyond cities. The contributors analyze instances when the urban poor coalesce to become visible, as well as when they strategically remain invisible, in both a physical and a symbolic sense. The articles start from the idea that, in a globalized world, virtual forms of travel and alliance can supplement or even replace physical movement. Following Cresswell (2010: 19), we understand mobilities here as the entanglement of three aspects: 'the fact of physical movement -getting from one place to another; the representations of movement that give it shared meaning; and, finally, the experienced and embodied practice of movement'. Physical movement can be taken as the 'raw material' from which mobilities are produced. A mobilities approach to migration, for instance, entails not only a study of the physical movement of people between and across places, but also entails considering the popular and official representations of these movements and the embodied practices involved. Virtual movement refers to the forms of communication, alliance and exchange enabled through the circulation of images and information. We see mobilization as the process, central to the formation of political actors, of making resources (such as manpower, money, information or images) available for the collective making of claims (Tilly and Tarrow, 2006: 74). By analyzing the flows, networks and imaginaries that influence possibilities for physical movement and social mobilization across and beyond the city, this symposium aims to share some fresh theoretical insights on the relationship between im/mobility and urban poverty. The rapid growth of the world's urban population over the past decades has spurred social scientists ...