The remarkable thing about this book is that it should not have appeared years ago. Considering the deluge of books on the prevention of war that has poured from the press it is astonishing that no one should have attempted to review the earlier history and development of efforts to preserve peace. Fortunately the subject has been taken in hand by a competent and scholarly person. This is an admirable survey of the movement as it developed during the last century. Mr. Beales, studying the early peace societies that sprang up after the Napoleonic Wars, shows how these first organizations worked out a complete body of theory, which, despite all trials and tribulations, has persisted down to the present time. The author is well acquainted with the literature of the subject, and has done a considerable amount of original research. There is a good bibliography, which will serve as a guide for further study of the problem. On the whole, the book fills a need and should not be neglected by those interested in the furtherance of peace.