Cities are a conundrum. They are at once spaces of connectivity and marginalisation, optimism and injustice. Rapid urban growth, persistent structural oppression, and the limitations of urban governance are issues that city dwellers face. But for some, living in cities also results in improved economic standing, stronger capabilities, and expanded freedoms. The Security at the Margins (SeaM) project sought to explore these tensions and contradictions. Funded by the Economic and Social Research Council (ESRC) and the South Africa National Research Foundation (NRF)—SeaM was a three-year collaboration that brought together the University of the Witwatersrand, the University of Edinburgh, local government, and civil society partners to better understand, and respond to, marginality in urban South Africa, Kenya, and the United Kingdom. The hope was to create the foundations for a long-lasting, international, inter-institutional partnership. This publication features research conducted during the SeaM project.