This article examines the effects of social and ethnic classroom composition and tracking on students' school satisfaction as an indicator of well-being and socioemotional outcomes in school. Analyses were based on a longitudinal school achievement study in Hamburg (Germany) with a sample of 5,941 students in 331 classes in secondary school. Multilevel analyses showed that, in classes with a more favorable social composition and a higher percentage of immigrants, students achieved higher levels of school satisfaction at the end of Grade 8. Regarding the developments of school satisfaction in Grades 7 and 8, the findings were similar but also indicated a stronger "confoundation" of compositional and tracking effects. It is concluded that because of segregation in secondary school, differential school environments do not only affect achievement but also emerge regarding socioemotional outcomes. Cross-level interaction analyses revealed gender-specific effects: Girls were found to be more susceptible to classroom composition and stronger benefit from attending academic tracks.