Despite recognition of bullying as a serious school and social problem with negative effects on students' well-being and safety, and the overlap between aggressive bullying acts and delinquent behavior, few empirical studies test the applicability of criminological theories to explaining bullying. This limitation in research is especially evident in studies of non-Western countries. Using longitudinal data on 2,817 South Korean youth, the current study attempts to fill the gaps by examining whether general strain theory can explain school bullying. As the theory suggests, youth who experience victimization by peers and conflict with parents are more likely to engage in bullying. However, there is limited evidence of the expected interaction effects between strains and conditioning factors. Inconsistent with general strain theory, parental attachment and positive relationships with teachers do not condition the effects of strains, and anger is not a mediating variable. Implications for interventions and for future research are discussed. (Contains 4 tables.)