This text aims to connect school organization theory with the school effectiveness knowledge base. Each chapter presents a comprehensive overview of the knowledge base on the central theme and addresses the question of what is known about the subject as a school effectiveness-enhancing condition. The conclusion discusses insight into the school organizational factors influencing the effectiveness of schools, and presents a proposal for the further integration and cross-fertilization of both approaches, which is being formulated with the aim of improving understanding of how schools function and which factors make them effective.