Inclusive school climates have been related to more friendly and equal intergroup relations among majority and ethnic minority youth. Yet, comprehensive research distinguishing majority and ethnic minority group perspectives on both social and institutional inclusion, and looking beyond individual perceptions of inclusion is missing. Taking a multi-group and multi-level approach, we assessed the actual social climate (aggregating majority intergroup attitudes within schools) and institutional climate (coding school diversity policies); and we tested associations with intergroup relations (i.e., individual intergroup bias and contact) and school performance (i.e., self-reported Dutch language grades) as individual outcomes for both majority and minority youth. To this end, we draw on a large-scale survey of 1814 native-origin majority and 1068 Turkish- and Moroccan-origin minority youth in the same 65 Flemish-Belgian middle schools. As expected for majority youth, a more inclusive ingroup social climate predicts less intergroup bias; and more social and institutional inclusion jointly predict more intergroup contact with minority peers. For minority youth, an inclusive outgroup social climate predicts higher Dutch grades; yet social and institutional inclusion were unrelated to their intergroup attitudes or contact.