The purpose of this study was to determine whether pro-bullying attitudes mediate the relation between affective and cognitive empathy and a student's willingness to intervene in support of a bullied peer. Participants were 764 early adolescents (372 boys, 392 girls) from the Illinois Study of Bullying and Sexual Violence (ISBSV). As predicted, pro-bullying attitudes successfully mediated the prospective relation between affective empathy and bystander intervention but failed to mediate the relation between cognitive empathy and bystander intervention. These results indicate that affective empathy may promote bystander willingness to intervene on behalf of a bullied peer by inhibiting pro-bullying attitudes. Intervention strategies designed to enhance affective empathy and challenge pro-bullying attitudes in bystanders may be of assistance in reducing bullying behavior.