The present study examined links between perceived teacher unfairness and bullying behavior in early adolescence, and the potential mediating role of instrumental social goals (specifically, agentic and separate goals). Based on social information processing theory, our model of proactive aggression was evaluated using path analysis in a sample of 662 Italian students aged between 11 and 13 years old (mean age = 12.55, SD = 0.99; 50.6% males). Results showed that perceived teacher unfairness positively relates to bullying, and that this relationship is partially mediated by the endorsement of instrumental goals. Our findings offer promising implications for future research and for intervention programs that aim to prevent school bullying through modifying the classroom context.