Violence among students at school is an ever-growing problem. Bullying can be defined as all forms of repeated physical or mental violence performed by an individual on another person who is not capable of defending him/herself (Roland & Idsoe, 2001). The three studies conducted here reveal some of the characteristics and implications of this type of aggression. Whether the attacker(s) or the attacked, all protagonists in a bullying episode suffer the consequences of this behavior. Study 1 showed that students who were both victims and bullies had the lowest self-concepts in all areas studied. Victims exhibited inferior self-concepts to bullies, who in turn obtained lower scores than students not involved in bullying at all. Study 2 showed, as expected, that the group of bully/victims reported more psychosomatic problems than all other groups. In addition, there was a positive link between behavioral problems and the onset of psychosomatic disorders. Study 3, which was mainly exploratory, looked at the traumatic impact of bullying and the emergence of addictive behavior. Children who had vivid memories of being the victim of an aggressive act manifested a high level of post-traumatic stress, although no link was observed between post-traumatic stress and the type of aggression (physical, verbal, or relational). A dependency relationship was found between post-traumatic stress and substance use. The results of these studies suggest that the many complexities of the different protagonists of bullying should be taken into account in view of developing servicing that is geared to each individual. (Contains 12 tables and 1 note.)