Does economic interdependence make states more peaceful or create vulnerabilities that can lead to war? Liberal and realist scholars have long debated this question, agreeing only that the historical record does not lend itself to simple theories. In this landmark book, Copeland argues that these debates have not adequately factored in the expectations of leaders concerning the future trade and investment environment. In some instances, liberals are correct: state leaders have positive expectations about the future and thus see the benefits of keeping the peace and the high costs of war. In other instances, realists get it right: state leaders are pessimistic about the future and fear economic decline and the loss of access to foreign trade and investment, leading them to think that war now is better than submission later. Copeland develops this sophisticated “trade expectations theory” of war and uses it to explore a number of cases of great-power conflict in the nineteenth and twentieth centuries before applying it to contemporary U.S.-Chinese relations. Copeland argues that the optimistic expectations of China’s leaders hinge on their confidence that oil and trade flows will remain open and stable—a mindset that might change in the coming decades if the United States moves toward a policy of containing and economically coercing China.