Drawing on sixteen months of ethnographic fieldwork in a poor and notorious neighbourhood, this dissertation examines how evolving dynamics of urban violence have affected life in a Guatemala City gang territory. The maras of Guatemala, El Salvador, and Honduras - the gangs that help give these countries some of the world's highest homicide rates - have changed dramatically in their group cultures and criminal economies since they appeared in the 1990s. I trace what I call the mara's predatory turn: the elaboration of an extortion economy, which has had far-reaching consequences for the relationship between gang cliques and their barrios. This transformation has re-shaped the experience of chronic insecurity in the communities that maras operate from: inhabitants report that it is now less manageable, less predictable, and more frightening. They speak of a heightening of danger in their lives brought about by the decline of certain local norms and mechanisms that had previously moderated gang violence and bolstered community resilience. Local narratives of insecurity and decline illuminate when, how, and why violence disrupts and disorders social life. What many informants emphasized was not a cataclysmic appearance of violence in their lives, but rather a catastrophic breakdown in the mechanisms that had controlled it. In this distressing context, residents struggle to minimize their insecurity and to reclaim or create forms of order. I examine two principal ways that they seek to do so: by working to maintain a moral order based on narratives about the neighbourhood and its values or 'codes', and by looking to external providers of order in the state and its security forces. Exploring the complex relationships and interactions between inhabitants, gang members, and state forces in this barrio, I contribute to academic debates about local and state responses to insecurity in Latin America and propose modifications to prevailing models of state and criminal 'governance' in marginal urban communities.