This document discusses the school effectiveness knowledge base and its usefulness for school improvement. It defines school effectiveness as the extent that student outcomes are influenced by modifiable conditions within the school, such as financial resources, management practices, or the curriculum. The document also outlines several theories that can help explain school effectiveness, including contingency theory, chaos theory, and cultural leverage theory. It concludes that school effectiveness research has primarily focused on instructional practices and school culture as the most impactful areas for improving student outcomes.