School engagement is important in promoting adolescents' academic and socioemotional outcomes. We explored whether sixth-grade students' (N = 571, M[subscript age] = 11.27, 52% female, 50% racial/ethnic minority) school engagement at the end of the academic school year was facilitated by their perceptions of teachers' classroom practices and support. Data were from a longitudinal study on Developmental Designs (DD)--a community-building and engaged-learning teaching approach designed to meet adolescents' developmental needs for autonomy, belonging, and competence. On average, student-perceived teacher support partially mediated the positive relations between perceptions of teachers' DD classroom practice use and students' school engagement. Results highlight the interrelatedness of teachers' instructional and affective practices in supporting early adolescents' school engagement, and suggest the potential benefits of school-based socioemotional initiatives focused on such teaching practices.