Immigrant and minority youth are at risk of experiencing victimization due to their ethnic, cultural, or religious background. Despite an increasing number of studies that aims at understanding the consequences of being the target of such negative experiences, little attention has been paid to the factors that might counteract the occurrence of ethnic victimization. The present study aimed to address this gap in knowledge by investigating the possible role of school context. Specifically, the present study examined the extent to which perceived positive contact norms in class and teachers' reactions to ethnic victimization are linked to engagement in ethnic victimization. It also examined whether such links differ across adolescents with different levels of tolerance toward immigrants. The sample included 963 adolescents residing in Sweden (M-age = 13.11, SD = 0.41; 46% girls). The results showed that perceived positive contact norms in class were associated with a lower likelihood of engagement in ethnic victimization across youth with different levels of tolerance toward immigrants. When adolescents perceived their teachers as not tolerating ethnic victimization, those with high levels of tolerance were less likely to engage in it. However, teacher reactions did not affect the behaviors of adolescents with low and moderate levels of tolerance toward immigrants. The findings indicate the importance of classroom context and teachers in counteracting negative interactions among students of diverse backgrounds.