Music historiography has traditionally been based on ‘methodological nationalism’, the assumption that the nation state is the ‘natural’ context of analysis. As a result, migration tends to be treated as an exception to the rule of nationhood with its comforting myths of belonging and tradition. By contrast, this chapter argues that modernist music can be regarded as the music of exile. It focuses on the ‘normality of migration’, encompassing both forced and voluntary migration, and it covers areas such as the role of international composition teachers and the ‘dodecaphonic diaspora’, the way serialism came to be associated with resistance to fascism and migration. In addition to presenting individual case studies, it seeks to quantify the commonality of migration, using the composers performed at the Annual Festivals of the International Society of Contemporary Music (ISCM), as a statistical basis. What this demonstrates is that, although mobility may not be the norm, neither is it an exception. Furthermore, it is one of the ways in which the transnational network that is integral to musical modernism has come into being.