In this monumental work, Vernon Ruttan has shared with us 30 years of study and research on the economics of technological change. The book covers an enormous literature, and each of its fourteen chapters has a bibliography as long as that of many full books. Oxford University Press has taken the unusual step of providing an author index, which I estimate contains at least 1,500 names, including a substantial subset of the membership of the Economic History Association. The book purports to cover the enormous literature on the economics of technology produced in the past fifty years. It succeeds admirably. While the author's own interests and predilections inevitably bias the coverage, and while some areas are not treated quite as thoroughly as others, the author's encyclopedic knowledge and his fair and informed treatment of the many confused and confusing contributions to an endlessly fascinating but somewhat incoherent and inconsistent literature make this book indispensable as a source and handbook. It seems a fair prediction that this book will be more often consulted than read cover-to-cover, with some chapters assigned to advanced undergraduates. But it is hard to think of many readers of this JOURNAL who will be able to afford not to have this book on their office bookshelf, next to their copies of the classics by A.P. Usher, Thomas P. Hughes, and David Landes.