Although peer influence is a salient predictor of delinquency, how it operates in the etiology of runaway behavior is not fully understood. Using data from the National Longitudinal Study of Adolescent Health, this study demonstrates the importance of taking peers into account in understanding the etiology of running away. The findings suggest that peer deviance is strongly associated with adolescents' decision to run away, independent of social network characteristics and their own deviant and conventional behavior, parental attachment, and school bonding. However, the causal process that links peer characteristics and running away remains unclear. More studies are needed to disentangle the underlying reciprocal and interactional relationships among peers, individual behavior, and social contexts such as family and school. (Contains 3 tables.)