Since peer violence is a common and perpetual societal problem its causes and effects are the subjects of numerous research papers. In this paper peer violence has been defined, its basic forms and characteristics explained and the frequency of certain forms of peer violence in children of school age have been highlighted. There are two fundamental forms of peer violence: classic and electronic violence (Bilić, 2018). Their differences, similarities and mutual connections have been explained. Violence in this work is observed as a tripartite relationship since not only does it involve a victim and a bully but also an observer. All of the participants of the violence have been described and their division listed. In this work the role of the peers that indirectly participate in the violence has been pointed out and the message that it sends to the others that participate in it. Peer help and support to the victim is very important. Peers that decide to intervene and help the victim are called the defenders of the victim. In this work their role as well as everyone’s that participate in the violence is visually shown in Olweus' circle of violence. Violence also commonly happens without the use of physical force. Some forms of violence are less noticeable but not less harmful so in this work they are explained as hidden violence. Since violence can also happen between girls the subcategories of aggressive behavior represented amongst them have also been explained. In this work the results of research into the consequences of participating in peer violence have been shown. Since children can have serious consequences after experiencing violence which can manifest within all the participants of peer violence it is important to prevent it and in doing so the school plays a big part. In this work various programs of prevention of violence amongst children that are used in the world and in the Republic of Croatia have been described. It is important to make the pupils, parents and workers within the school aware of their role in the lessening or suppression of violence and to point it out.