For those who think that the legalist approach to international relations began and ended with Woodrow Wilson, this book will be a surprise. Boyle shows that by the turn of the century, the United States already had a comprehensive agenda for extending law into international relations. Furthermore, it was initially championed by more Republicans than Democrats and even survived the debacle of the League of Nations' collapse. Focusing in detail on a series of American legal-institutional initiatives between the 1898 Spanish-American War and the 1919 Versailles peace settlement (such as mandatory international arbitration agreements and the International Court of Justice), the author reveals a larger legalist orientation that infused much of American foreign-policy thinking during those years and laid the foundation for further initiatives after 1945. The book tells a fascinating story of law and institutional innovation -- but misses the opportunity to explain why some initiatives succeeded and others failed.