This contribution is dealing with the problem of bullying as an intentional, repeated violence among pupils in school setting. Its goal is to discuss the specifics and the research of this weighty phenomenon in the worldwide context. It also brings the quantitative and qualitative research conclusions focusing on bullying and bully in secondary school setting in Slovakia. The main goal of this research was to analyse the phenomenon of bullying with the focus on examining the social climate of classroom where bullying is present, the social position of aggressor, his personal characteristics, the way aggressor perceives bullying, aggression, and how aggressor evaluates his or her family background. As it results from this research, the most frequent place of bullying is classroom with a low cohesion and a bad emotional atmosphere. In classroom aggressor has an ambivalent status, his position within a group is complicated, he belongs to the controversial pupils. There is an ambivalent relationship between the group as a whole and the controversial pupils. Aggressors feel in classroom relatively good, they show satisfaction with it. They are in a positive, optimistic and balanced mood. They are self-confident, self-reliant, spontaneous, relaxed, not controlling their behaviour. The increased rate of spontaneous and reactive agression was not proved. Aggressors consider bullying as something usual, they perceive their victims negatively, and they do not perceive their own behaviour as „the real bullying“. The aggressors who are not satisfied with their own family background, live in an incomplete family where parents are divorced, they evaluate their relationships with parents as conflicting and their relationship with father as more negative, and refer to this kind of relationship as to emotional emptiness, distruss and lack of interest.