Available open access digitally under a CC-BY-NC-ND license. This book examines the significance of both historical and contemporary inequality in shaping diplomatic disagreements in international relations. The author demonstrates that the North-South divide has endured into the 21st century by drawing on three decades of data measuring the foreign policy positions of states on divisive global issues, including new text-based measures of international priorities within the United Nations General Assembly. This divide reflects the dissatisfaction of many states of the Global South with the post-Cold War international order, owing to historical legacies of unequal development. Wide-ranging and rigorous, this new empirical investigation demonstrates the ongoing relevance of material inequality for international politics and the multilateral system.