In October 2019, unprecedented mobilizations in Chile took the world by surprise. An outburst of protests plunged a stable democracy into the deepest social and political crisis since its dictatorship in the 1980s. Although the protests involved a myriad of organizations, the organizational capabilities provided by underprivileged urban dwellers proved essential in sustaining collective action in an increasingly repressive environment. Based on a comparative ethnography and over six years of fieldwork, Mobilizing at the Urban Margins uses the case of Chile to study how social mobilization endures in marginalized urban contexts, allowing activists to engage in large-scale democratizing processes. The book investigates why and how some urban communities succumb to exclusion, while others react by resurrecting collective action to challenge unequal regimes of citizenship. Rich and insightful, the book develops the novel analytical framework of 'mobilizational citizenship' to explain this self-produced form of political incorporation in the urban margins.