This special issue was originally founded upon a symposium, 'Global migration in a changing UK', held on the 10th of May 2017, at the Manchester Metropolitan University, UK, discussing how the changing nature of global migration is shaping the local economy, culture and society of Manchester, an emerging global city within the UK. These discussions were set within the context of significant economic and political developments, such as the increasing neo-liberal public spending and policy choices of the UK government and the climate of 'Brexit'the UK decision to withdraw from the European Union, leading to UK political policy and public opinion clouded in fear and uncertainty. Global migration is currently a highly politicized issue (Porter & Russell, 2018) and the political context of the UK has led to a fall in migration numbers (Syal & O'Carroll, 2018), bucking global trends. The world-leading authority on global cities, Saskia Sassen the keynote speaker at the symposium, drew on her recent work on Expulsions (2016), demonstrating how the term migration actually conceals multiple forms of socio-economic dislocation and predatory formations, whereby assemblages of knowledge, interests, and outcomes, lead to expulsions of people, social groups and livelihoods. The persistent effects of neo-liberalism lead to damaging consequences and vulnerabilities for migrants. The collection of papers here develops these themes by focussing upon the relationship between neo-liberalism, contemporary forms of migrant transnationalism and precarity, within a wider context than the city of Manchester.Definitions and discussions of transnationalism often distinguish between 'broad' and 'narrow' transnational social practices (Basch, Glick Schiller, & Szanton Blanc, 1994;Itzigsohn, Cabral, Hernandez Medina, & Vazquez, 1999), or transnationalism 'from above ' and 'below' (Smith & Guarnizo, 1998), with the former referring to the transnational activities of global economic institutions and nation-states and the latter relating to networks of relationships between migrant populations and people and places within an original sending society. Studies of the migration-development nexus have focussed heavily upon narrow transnationalism, with many celebrating the progressive consequences of migrant transnationalism, in terms of both the social mobility of migrants and the 'development' of sending societies. Whilst it has been recently recognised, not least within the pages of this journal, that the relationship between migration and development is more complex and contradictory than these celebratory discourses suggest, there has been insufficient attention to the mutually constitutive relationship between broad and narrow transnationalism. Migrant social and transnational practices take place within, shape and are shaped by wider, broad,