Background: Many studies have shown that school belonging is crucial for students' school adjustment, but the construct has been operationalized in different ways. Moreover, most research has focused on adolescents and not compared its antecedents for ethnic minority versus majority students. Aims: Based on Goodenow and Grady's (1993) seminal paper, we examined classroom identification as a central aspect of school belonging in minority and majority preadolescents, and predicted it from relationships with peers and teachers, taking into account classroom ethnic composition and perceived multicultural teaching. Sample: Participants were 485 grade 4-6 students from 39 classrooms in Dutch primary schools. Of these children, 68 had a Turkish background, 72 had a Moroccan background, and 345 had a native Dutch background. Methods: Participants completed questionnaires at two waves (4.5 months apart). We used self-reports to measure classroom identification at both waves, and student-teacher relationship closeness and conflict, multicultural teaching, and peer friendship and rejection at Wave 1. We conducted multilevel analyses to predict classroom identification at Wave 2, while controlling for classroom identification at Wave 1. Results: Children of all ethnicities reported more classroom identification over time if they were less rejected by their peers and had more co-ethnic classmates. For minority children, both closeness and conflict with the teacher predicted less identification, but the effect of conflict appeared to result from their ethnic underrepresentation in the classroom. Conclusions: Negative peer relationships can undermine classroom identification, and the student-teacher relationship has special significance for ethnic minority students.