Separate sections of the chapter address young children who kill and adolescent murderers. The latter section focuses on psychological disorder and youth homicide, the intelligence of young homicide offenders, the home environments of youth murderers, the involvement of youth murderers in other antisocial behavior, substance abuse, and other social difficulties. The authors suggest that the adolescent murderer tends to be a male who is unlikely to be psychotic or mentally retarded, to do well in school, or to come from a home in which his biological parents live together in a healthy and peaceful relationship. Rather, he is likely to have experienced or to have been exposed to violence in his family and to have a prior arrest record. More so than juvenile homicide offenders in the past, he is likely to use/abuse drugs and alcohol. Remaining sections of the chapter discuss empirical studies of juvenile homicide offenders and factors that contribute to the increase in juvenile homicides. The latter section discusses situational factors, societal influences, resource availability, personality characteristics, and the cumulative effects of these factors in historical context. Biological factors are discussed as well. 150 references