In this article we develop and test a multi-level theory of the sources of self-control among adolescents. We argue that neighborhoods are an important structural source of self-control. We test this idea using data from the National Longitudinal Study of Adolescent Health (n = 9,171). Results from a multilevel structural equation model indicate that neighborhood disadvantage is a significant predictor of adolescent self-control, controlling for demographics, family characteristics, and social integration. Implications for future research on the role of neighborhood context in the development of self-control among youth are discussed. In addition, we discuss the implications for policy of multilevel theorizing.