The examination of a large, urban, East Coast high school provides an enlightening chapter in the implementation and validation of a professional learning community (PLC) as a strategy for school improvement. The teachers of this East Coast school were accustomed to working in isolation, and the students demonstrated numerous areas of academic deficiency. Thus, teachers garnered the support of some administrators to employ the principles of professional learning communities to change the culture of the school and to address several issues that contributed to the failure of the school. The PLC initiative called for the implementation of new strategies and processes beginning with collaborative teamwork. Teachers discussed teams as a strategy for school improvement, and the school-wide conversation then migrated to smaller niches, such as department meetings. [This report was produced by the Massachusetts Association for Supervision and Curriculum Development (MASCD).]