This book provides insights into the processes and motivations involved in group formation and joining, as well as into group cohesiveness and dis-integration, and the processes whereby individual members disengage or are unable to do so. Various forms of interaction between the group and the social environment will also have great impact on the fate of the group and its members. These are all processes and mechanisms that can be influenced through prevention and intervention measures – and more effectively so if action is based on knowledge of both the general phenomenon as well as of the local situation. The text provides a detailed description of several intervention methods and programmes that have been developed to address problems of violent and/or racist youth groups and violence, and that have been demonstrated to have some success in that respect. The main target groups are youth workers, social workers, teachers, police officers, municipal administrators, policy makers and other practitioners who are in positions where they have to handle emerging problems of racist and violent youth groups, as well as students to these professions.