This paper explains how organizations otherthan schools and governing agencies affect thescope and pace of change in American education.In particular, the paper discusses a set oforganizations operating in what can be calledthe school improvement ``industry'' in the UnitedStates, that is, a group of organizationsproviding schools and governing agencies withinformation, training, materials, andprogrammatic resources relevant to problems ofinstructional improvement. The paper shows howthe structure and functioning of theseorganizations explain patterns of change inAmerican education – including why schools inthe United States experience wave after wave ofinnovation and reform while at the same timemaintaining a stable core of instructionalpractices.