The present research investigates the existence of verbal aggression and its causes in Tehran middle schools. Subjects consist of 498 students (boys and girls) from Tehran educational districts. Research findings highlight the fact that there exits verbal aggression not only between students but also between teachers, non-teaching staff and students. There is a significant difference between boys and girls: boys being more aggressive than girls. The most important factors causing the verbal aggression of students is seen by them as their individual characteristics, the school failure and excessive amount of homework. The students see the cause of teachers verbal aggression as being the teachers characteristics and the crowded and negative atmosphere of the classroom. Boys express their anger more by verbal and physical aggression than girls