This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is about a movement to change schools on a grand scale. It provides a comprehensive understanding of the dynamics of school change in the era of externally developed reform designs. The book focuses on the large-scale reform movement more generally, which involves not just the reform designs but also the global movements to implement educational reform across an entire district, state, or nation. Such large scale reform efforts are currently occurring in such diverse places as England, the Canadian province of Ontario, Chicago, Boston and San Diego, among others. The book includes data from an in-depth qualitative study of implementation and teaching in three Success for All schools in California. It develops a novel theoretical framework for making sense of reforms going to scale.