Societies have become super-diverse due to migration and globalization. Many mainstream classroom teachers feel managing the linguistic variety children bring to school is challenging. This often leads to restrictive language policies. Inquiry on multilingualism has given us insight into the multilingual realities of pupils, which enables us to focus on how the integration of these realities in school life might influence pupils’ academic results and well-being. This study explores how teachers’ tolerant practices toward multilingualism might mediate the relationship between schools’ linguistic diversity and pupils’ school belonging. The survey data stem from 67 Flemish primary schools, in which 1255 teachers and 1761 pupils participated. Stepwise multilevel modeling displayed that teachers’ tolerating practices towards multilingualism statistically compensate for the negative effects of linguistically diverse schools on school belonging.