The theory of low self-control has been shown to be a valid predictor of a wide variety of criminal and deviant behaviors. However, a limited number of studies were conducted to understand the relationship between low self-control and bullying and the effects of opportunity factors (i.e., parental supervision, association with other bullies, negative school environment, and disciplinary measures used by teachers) on bullying in the context of low self-control theory. The present study, using a sample of nearly 300 youths, examined the effects of low self-control and opportunity factors on various types of bullying behaviors. Results indicated that youths with low self-control were likely to physically and psychologically bully, consistent with the theory’s prediction. When opportunity measures were introduced, they were stronger explanations of bullying than low self-control, especially association with other bullies and youth who experienced disciplinary measures by their teacher. Negative school environment was a significant predictor of psychological bullying but not for physical bullying. Theoretical and policy implications are discussed.