Two landmark policy interventions to improve the lives of youth through neighborhood mobility-the Gautreaux program in Chicago and the Moving to Opportunity experiments in five cities-have produced conflicting results and created a puzzle with broad implications: Do residential moves between neighborhoods increase or decrease violence, or both? To address this question we analyze data from a subsample of adolescents ages 9-12 from the Project on Human Development in Chicago Neighborhoods, a longitudinal study of children and their families that began in Chicago, the site of the original Gautreaux program and one of the MTO experiments. We propose a dynamic modeling strategy to separate the effects of residential moving over three waves of the study from dimensions of neighborhood change and metropolitan location. The results reveal countervailing effects of mobility on trajectories of violence: Whereas neighborhood moves within Chicago lead to an elevated risk of violence, moves outside of the city reduce violent offending and exposure to violence. The gap in violence between movers within and outside Chicago is explained not only by the racial and economic composition of the destination neighborhoods, but the quality of school contexts, adolescents' perceived control over their new environment, and fear. These findings highlight the need to consider simultaneously residential mobility, mechanisms of neighborhood change, and the wider geography of structural opportunity.