Since the late nineteenth century, urbanization has been known to be a significant risk factor for mental illness (Burr, 1903). And yet central epidemiological, psychiatric and sociological questions around the specificity of this relationship still remain unanswered. Such questions include: what is it, exactly, about the ordinary life of the city that produces such pathological states? What specific roles are played by such phenomena as urban poverty, deprivation, overcrowding, social exclusion, racism, and violence to mental distress? What mechanisms are at stake, at both the biological and sociological levels, and how do these mechanisms interact? These questions have been addressed in a range of literatures – principally urban sociology and psychiatric epidemiology –  but these have rarely spoken to one another across disciplinary lines. Thus psychiatric research has suggested various social phenomena that tie mental illness and the social lives of cities together, such as density (Vassos et al., 2012) or stress (Selten and Cantor-Graae, 2005), but this literature has rarely been broght into contact with discussions from the social sciences about the consequences of the urban experience for mental life (Tonkiss, 2013; Amin, 2015).   This is particularly signficant in the case of migrants, for two reasons.  First, contemporary urbanization across the globe is driven largelyby rural to urban migration (https://esa.un.org/unpd/wup/Country-Profiles/).  Second, one of the most consistent research findings is that migrants, in cities, bear a disproportionately large share of the burden of urban mental illness (Li et al, 2006). Today, the effect of this disproportionate burden is felt, not in the Euro-American cities that fixated scholars in the late nineteenth and early twentieth centuries (Berlin, London, Chicago), but in the emergent mega-cities of the ‘global south’ – it is in cities like Shanghai Sao Paolo, Nairobi, and Mumbai, that the major intersections of migration and mental health are taking place today. This interdisciplinary workshop thus focuses on two central questions: (1) What specific aspects of migrant life in contemporary mega-cities are either producing or exacerbating the production of urban mental illness? (2) What insights might be gained by joining insights from sociology, urban studies, epidemiology, psychiatry and neurobiology, to understand how ordinary lives on migrant streets can sometimes generate the forms of distress that we recognise as mental disorder? Overarching these questions is a recognition that understanding the drivers of poor mental health in migrants is not just a question of mental health policy, but must also underpin development goals of alleviating poverty in emerging megacities. The workshop will thus consider what policy developments must be prioritised to secure and improve for mental health of migrants in contemporary megacities, and will ask how a biosocial account of migrant mental health might contribute to these developments.