This study examined the mediating role of self-blaming attributions on peer victimization-maladjustment relations in middle school and the moderating role of classroom ethnic diversity. Latino and African American 6th grade participants (N = 1105, 56% female) were recruited from middle schools in which they were either members of the numerical majority ethnic group, the numerical minority, or one of several ethnic groups in ethnically diverse schools. Peer nomination data were gathered in the Fall of 6th grade to determine which students had reputations as victims of harassment and self-report data on self-blame for peer harassment and the adjustment outcomes of depressive symptoms and feelings of self-worth were gathered in the Spring of 6th grade, approximately 6 months later. A mediational model in which self-blame partly explained the relation between victimization and maladjustment was supported among students from the majority ethnic group in their classroom but not among students from the minority group. The usefulness of including ethnic diversity as an important context variable in studies of peer victimization during early adolescence was discussed.