Why belonging? Why geography?As we begin writing this guest editorial an e-mail alert informs us of a call for papers for the Social and Cultural Geography Study Group of the RGS-IBG for 2009 which seeks papers``interested in the way the world works to produce social and cultural difference, engaging with key social science debates concerning identity, subjectivity, citizenship and belonging.'' This e-mail is indicative of the growth of recent research in geography which draws on belonging as a key concept. Sometimes, belonging is at the centre of the analysis but, more often, it is used in a way that implies a common understanding of what belonging is and why belonging is important. Needless to say, no such common understanding exists. Indeed, with the proliferation of belonging in human geography come the inevitable questions: what is belonging, how does one belong, and, importantly, what work does belonging as a concept do? In the introduction to this theme issue on``Geographies of belonging'' we reflect on the notion of belonging, explore the work that belonging does in contemporary social science, particularly human geography, and outline the contributions of the theme issue.Belonging is mobilised in a range of spheres within human geography. Indeed, it is clearly possible to belong in many different ways at many different scales. Belonging has formal and informal aspects, implied, for example, by ideas of formal and informal citizenship and civic identity (