Adolescent violence is a very visible violence in our modern society, where you just have to open the newspaper or the television and you find yourself right in the middle of it. In order to understand the scope of the problem, we need to look at the epidemiology of global violence. Each year, more than 1.6 million people world-wide lose their lives to violence and for every person who dies as a result of violence, many more are injured and suffer from a range of physical, sexual, reproductive and mental health problems. Violence places a massive burden on national economies in health care, law enforcement and lost productivity. We are talking about a major public health problem. Programs for intervention have been researched and long-term follow-up indicates that early intervention is working and even if such programs would seem to demand a substantial economic investment, they have been proven cost-effective in the long run. In this book, we have gathered presentations on bullying, aggression, violence, suicide and prevention from an international perspective.