There are scarce studies on bystanders' responses to racist hate speech. The present study was rooted in the general aggression model to examine the direct and indirect associations between witnessing racist hate speech and bystanders' active defending behaviors. Moreover, we examined if these associations varied as a function of the immigration background of bystanders. The sample included 3,225 7th, 8th, and 9th graders (51.7% girls, 37.2% with an immigrant background) from 40 schools in Switzerland and Germany. A multilevel mediation path model revealed that witnessing racist hate speech negatively predicted bystanders' active defending. It also had indirect associations with bystanders' active defending via low levels of empathy. Finally, associations were not observed in students with an immigrant background. The findings regarding the potential contribution of these results to preventing hate speech in school are discussed.