This paper focuses on the development of professional learning communities (PLCs) in schools, which are communities of educators tasked with improving student learning outcomes. The purpose of this paper is twofold. First, the paper explores the central tenets of an effective PLC and contributes a definition of the concept to address much of contextual ambiguity found within the literature. Secondly, the paper employs this definition to inform the development of a conceptual framework for understanding effective PLC operation in schools, which can be used as a guide for PLC implementation at both the school and system levels.