Juvenile homicide is a social problem that has remained a central focus within juvenile justice research in recent years. The term juvenile murderer describes a legal category, but it is purported to have significant scientific meaning. Research has attempted to conceptualize adolescent murderers as a clinical category that can be reliably distinguished from their nonhomicidal counterparts. This study examined 33 adolescents adjudicated delinquent or awaiting trial for murder and 38 adolescents who committed violent, nonhomicidal offenses to determine whether the two groups differed significantly on family history, early development, delinquency history, mental health, and weapon possession variables. The nonhomicide group proved more problematic on many of these measures. Two key factors did distinguish the homicide group: These adolescents endorsed the greater availability of guns and substance abuse at the time of their commitment offenses. The significance of this finding is discussed, and the implications for risk management and policy are reviewed