Research shows that sibling victimization may be as detrimental to adolescent outcomes as peer victimization. However, many questions remain unanswered with regard to protective parenting factors and consequences of sibling victimization among adolescents. This study tested a mediation model in which sibling victimization, predicted by parental monitoring, is associated with parent and peer-adolescent attachment as mediated through adolescent self-perceptions of social competence and self-worth. A three path mediation from parental monitoring [right arrow] sibling victimization [right arrow] adolescent self-perceptions [right arrow] peer-/parent-adolescent attachment was tested. Structural equation modeling results revealed that parental monitoring was negatively associated with sibling victimization for girls. For boys and girls, sibling victimization had negative direct and indirect effects on parent- and peer-adolescent attachment via adolescent self-perceptions of social competence and self-worth. Findings suggest that parental monitoring may be important in the prevention of sibling victimization and self-perceptions may be an important point of intervention for adolescents experiencing sibling victimization.