A review of time trends in homicide rates in the United States found that although there has been a significant decline in homicides committed by older offenders, homicides committed by juveniles have increased dramatically, beginning in 1985. An important factor in this growth has been a significant increase in the availability of guns to juveniles. By examining time trends in age-specific arrest rates for homicide (gun homicide compared to non-gun homicide) and similar trends in drug-related arrest rates (juveniles compared to adults), the role of gun availability, especially as it has increased through the recruitment of juveniles into drug markets, was identified as a probable cause of these homicide trends. Further examination of mortality rates -- due to gun homicides compared to non-gun homicides as well as gun suicides compared to non-gun suicides -- for various age and race groups also implicates gun availability as a key contributing factor in the increase in youth homicide. A discussion of policy implications focuses on the reduction of the availability of guns to juveniles, an attack on the gun markets selling to youth, and a reduction in drug markets, as well as the development of improved socialization for youth by the institutions that mold the behavior of youth. 10 figures and 28 notes