School-Wide Positive Behavioral Interventions and Supports (SWPBIS) is an evidence-based framework that aims to improve school environments and promote expected behaviors among students. SWPBIS primarily targets teachers' practices, and it is currently unclear how far it affects students' perceptions of these practices, even though such perceptions influence school outcomes. The present experimental effectiveness study therefore investigated the effects of SWPBIS on students' perceptions of three types of teachers' practices: behavior management, supportive practices, and encouragement of participation in school life. The study was conducted in 21 middle schools in France, among 6765 adolescents ("mean age" = 12.3 years; 51% girls) in 40 control and 44 SWPBIS grades (grades 6-9). Multilevel analyses were conducted, controlling grade-level students' perceptions at baseline. Results indicated that SWPBIS had a positive effect on students' perceptions of supportive practices and encouragement of participation in school life, irrespective of their initial levels. However, no significant effects were found for students' perceptions of behavior management. The study suggests that SWPBIS enhances students' perceptions of key teachers' practices. The implications for future research and practice are discussed.