This article introduces ABBL, the anti-bullying program for the transition to middle school, which was designed as a free, feasible, and easily applicable solution for teachers who, for any reason, cannot take advantage of comprehensive anti-bullying school-based programs. The ABBL, based on the identification of the causal risk factors and mechanisms that lead to bullying, aims to influence the peer group in such a way that students do not reward antisocial behaviors and are, instead, able to create supportive class atmospheres and strong networks of personal attachments. The evaluation of the program effectiveness showed that it reduced bullying in the classroom. Indications for wider implementations are presented together with the ready-to-use ABBL anti-bullying program (see http://blizej.org/abbl-antibullying-program/ ).