Legal socialization theory predicts that attitudes mediate the relation between legal reasoning and rule-violating behavior [Cohn, E. S., & White, S. O. (1990). Legal Socialization: A Study of Norms and Rules. New York: Springer-Verlag]. Moral development theory predicts that moral reasoning predicts rule-violating behavior directly as well as indirectly [Blasi, A. (1980). Bridging moral cognition and moral action: A critical review of the literature. Psychological Bulletin, 88, 1-45]. We present and test an integrated model of rule-violating behavior drawing on both theories in a longitudinal study of middle school and high school students. Students completed questionnaires three times during the course of 1 year at 6-month intervals. Legal and moral reasoning, legal attitudes, and rule-violating behavior were measured at times one, two, and three respectively. Structural equation models revealed that while moral and legal reasoning were directly and indirectly related to rule-violating behavior among high school students, legal reasoning bore no direct relation to rule-violating behavior among middle school students. The implications for an integrated model of reasoning and rule-violating behavior are discussed.