Why do some boys develop into troublesome youths who eventually get sentenced for violent crimes? In planning a strategy to fight violent crime, it is important to identify significant risk factors for violent criminal behaviour among adolescents and young men. In this study information from population-based registers covers various aspects both for children, aged between 15 and 27 years, and their parents: health (mental and physical), education, social networks, family violence, self-destructive behaviour, parental alcohol or drug abuse, and unemployment. First-time convicted offenders have an increased risk of coming from seriously disadvantaged families; they also seem to be characterized by unstable education and employment records (e.g. not graduating, no vocational training), occasional work, or long-term unemployment.