A. S. Neill was probably the most famous school teacher of the twentieth century. His school, Summerhill, founded in 1921, attracted admiration and criticism from around the world, and became an emblem of radical school reform and child-centred education. Neill claimed that he was a practical man, but this book reveals that Summerhill expresses a comprehensive and distinctive set of ideas. Whether he wanted to be or not, Neill was an important educational thinker with a powerful influence on current educational approaches and philosophy. A. S. Neill is the first book to examine this philosophy of education in detail. It begins by showing how Neill's fascinating life story gives clues to the origin of his ideas, and why they mattered so much to him. It goes on to explore the main themes of his philosophy, showing how they relate to the work of other great educational thinkers, and how they are novel. It also discusses whether there are lessons that could and should be learned by other schools from the original, alternative `free' school of Summerhill.