Scholars studying change in international relations during the modern and contemporary eras typically focus on the rise and decline of states and great shifts in the distribution of power. In this important book, Buzan and Lawson argue that this cyclical view of change misses a deeper transformation that unfolded during the nineteenth century and brought the world together into a single system. Capitalism and industrialization increased the world’s “interaction capacity,” bringing peoples and societies into closer contact while creating new divisions and inequalities. Meanwhile, Western nation-states grounded themselves in the rule of law at home while pursuing imperial goals across the globe. These modernizing dynamics propelled the rise of new ideologies, such as nationalism, liberalism, and “scientific” racism, that states used to legitimize their strategies in the game of great-power politics. For Buzan and Lawson, world politics today can be seen as the “downstream consequences” of this nineteenth-century arrival of “global modernity,” and the authors believe that these deep modernizing forces are still at work, ushering in a more “decentered” future in which power will become more diffuse.