Our study explores how various factors at individual and class level influence social participation among German secondary school students. Previous literature suggests that individual variables like academic achievement, migration background, and gender can impact social participation. Moreover, class-specific disparities may arise based on school track or -- in the sense of a homophily effect -- on differences in the distributions of gender and migration background. Over and above these effects, we hypothesize that the quality of teacher-student interaction plays a role in shaping students' social participation. We used hierarchical linear models with data from a standardized questionnaire administered to 876 pupils organized into 39 classes (5th to 7th grade) in 12 secondary schools. Our analysis shows that high-quality interaction between teachers and students is associated with higher levels of social participation among students -- measured both through self-perception and peer acceptance. Additionally, higher social participation scores were observed in higher track schools (Gymnasium) relative to lower school tracks. Finally, a gender homophily effect is observed only for peer acceptance. These insights have significant implications for both researchers and educators. In conclusion, this work underscores the importance of accounting for contextual characteristics when examining determinants of adolescent social participation.