The author of this article edited all Daphne du Maurier’s work for nearly forty years, from 1943 until she published her last book in 1981. The article discusses the qualities which made her a best seller, whose books are read and studied in universities all over the world, and provides insights into her skill as a writer, and into the links between her books and her own life. It describes how author and editor worked together, and seeks to throw light on du Maurier’s complex and often contradictory personality. There are also quotations from her letters, published here for the first time. Because of the author’s particular relationship with du Maurier, the article gives a new and personal insight into how so many world-famous books came into being.