This study investigates the unexpected emergence of a community of practice in a middle level mathematics and science methods course. The authors describe how preservice teacher participation in a collaborative, project-based service-learning experience resulted in the formation of a community of practice characterized by teamwork, meaningful practice, and shared resources. The article concludes with a twofold argument demonstrating how collaborative, project-based service-learning experiences potentially contribute to preservice teacher learning via the positive outcomes that emerge from participation in a community of practice, while also reinforcing preservice teacher commitment to the constructive pedagogy of service-learning.