The school, as a living organism, is influenced by the change in conditions and problems that arise. Consequently, the role of principal-leader is an especially demanding one, as it has to face contemporary challenges. The objective of this work is the study of bullying in schools among colleague teachers and the stance taken by the principal-leader, by comparing two articles. The articles we are studying and comparing, are considered by us representative, and come from America and Australia, respectively. We note that the particular research topic of bullying between colleagues has been limitedly investigated in Greece, as only one research has been carried out on this matter. Finally, as a way of addressing the issue we suggest the transformational of leadership model be implemented.