Despite the interest in juvenile homicide offenders, few studies have systematically examined their involvement in incidents involving specific victims. This study focused on one victim type, the killings of siblings. To date, siblicide research has been based primarily on case studies. Bivariate and multivariate techniques were used to systematically investigate offender, victim, and incident characteristics associated with fratricides and sororicides committed by juvenile homicide offenders in single victim, single offender incidents over a 32-year period (1976-2007), as recorded in the Supplementary Homicide Report data base. Juvenile sororicide offenders, relative to juvenile fratricide offenders, were significantly more likely to be female and to kill younger victims. The article concludes with a discussion of the findings in terms of past research, their implications for intervention and prevention, and directions for future research. Abstract published by arrangement with Springer.