This volume explores the determinants of state power, the strategic options of rising powers, the drivers of conflict in dynamic international systems, and American grand strategy past and present to achieve a more comprehensive understanding of the current era of great power competition. Leveraging insights from international relations, history, economics, and political demography, it offers rich perspectives on the competition among newly rising powers and long-dominant leaders in the international system. This book presents novel theories and innovative empirical investigations into the economic and demographic challenges confronting rising powers, along with new inquiries into these countries’ capacity to mobilize both their citizens and their militaries. While China’s grand strategy has attracted significant attention in recent years, these authors look beyond U.S.–PRC relations by considering the war proneness and strategic repertoires of rising regional powers, including India and Russia. Yet, the possibility of great power war remains a justifiable concern. This book examines the so-called Thucydides’s Trap by exploring both its explanatory power in the conflict that inspired its name, the Peloponnesian War, and the possible mechanisms for averting war between the two most powerful countries in the current era. Finally, several challenges confronting the United States are discussed, including climate change, competition over the interpretation of the international Women, Peace, and Security agenda, and the durability of America’s commitment to upholding the liberal international order. The Sources of Great Power Competition brings together many of the most influential scholars to engage in lively debates about the current and future international system. It will be of interest to foreign policy practitioners and scholars of grand strategy, the causes of war, alliance politics, norms and narratives in foreign policy, power transitions, and international hierarchy.