This article examines the impact of a service-learning program based on positive youth development and social and emotional learning principles in two high-poverty urban middle schools. A longitudinal mixed-methods design was implemented, and qualitative data analysis yielded unexpected results associated with the professional development of teachers and social workers involved in the program. The data suggests that participation in weekly program sessions for students contributed to positively shifting adults' perceptions of students, and expanding the repertoire of classroom management strategies, which, in turn, overflowed into other areas of the school culture. This case analysis proposes a theoretical shift to interdisciplinary professional development that incorporates social and emotional learning strategies implemented in the classroom and through service learning as part of a comprehensive program.