Transnational studies pose a challenge to social work that is reflected on at least two distinct levels. First, there is growing evidence that social relations and practices cannot be analysed only within the confines of the nation-state anymore, as numerous transnational processes can be observed that transcend those confines at the level of individuals, communities, or organisations. Second, the debate about the transnationalisation of the social world (Pries 2008) shows that the neglect of these transnational processes is a symptom of an inherent weakness in social science methodology and theory building. The social sciences have overlooked the importance and the changing meaning of the nation, the nation-state, and its institutions, e.g., territory, law, or authority (Sassen 2008). This blind spot, referred to as methodological nationalism (Wimmer and Glick Schiller 2002), has hindered the exploration of transnational processes already underway for some time.