Urban security (or public safety), rather than a "social problem" tackled neutrally, is an issue of political contestation, owing to its threefold gist as right to not be victims of crime, policy goal, and social demand. This article, highlighting how planning research has neglected to engage with contemporary paradoxes of security, makes the case for a critical approach to crime prevention and explores the embeddedness of urban security in planning practice in the Lisbon Metropolitan Area. We debate the relations of urban security with changing planning paradigms and political approaches around the vertical (multilevel/multiscale) and horizontal distribution of planning practices.