Violent crimes committed by children and adolescents shatter society’s warm images of youth and innocence, and frequently result in public outcry. Who are these young people, why do they do it, and how can criminal justice play an effective part in the spheres of treatment and prevention? This paper, which provides an overview of this topic, constituted Gwyneth Boswell’s Inaugural Professorial Lecture, given at De Montfort University on 27th March 2003.