In this seminar I will argue that we should rethink the experience of living in the city in the light of recent developments in the sciences of life. We now know a great deal about the corporeal and cerebral impacts of the varieties of forms of life that we call ‘urban’. I will argue that social scientists need to work with researchers in the life sciences to understand how urban experience, and urban adversity 'gets under the skin' and shapes the bodies and brains of urban citizens and denizens. I will discuss the idea of ‘the neurosocial city,’ that I have developed with Des Fitzgerald. This concept aims to grasp the ways that the forms of life in the conglomerations we call cities are simultaneously lived and transacted through the living bodies and brains of ‘each and of all’ – the individuals and the multitudes who inhabit urban space. I will outline the argument that my colleagues and I are developing in our current research on the mental consequences of migration into megacities, and draw out the implications, on the one hand for our understanding of the vital lives of cities, and on the other, for the relations between the social sciences and the life sciences today.