John A. Vasquez’s The War Puzzle provided one of the most important scientific analyses of the causes of war of the last two decades. The War Puzzle Revisited updates and extends his groundbreaking work, reviewing recent research on the onset and expansion of war and the conditions of peace. Vasquez describes systematically those factors associated with wars to see if there is a pattern that suggests why war occurs, and how it might be avoided, delineating the typical path by which relatively equal states have become embroiled in wars in the modern global system. The book uses the large number of empirical findings generated in the last twenty-five years as the basis of its theorizing, and integrates these research findings so as to advance the scientific knowledge of war and peace.