Nationalism in the modern world began in European metropoles but spread throughout the world system in the form of anticolonial nationalism. While many studies have explored the former, this essay systematically examines the latter. Based upon an original database of 124 cases, we test multiple theories that might account for the origins and spread of anticolonial nationalism. We adjudicate between cultural-cognitive approaches emphasizing the discursive bases for national imaginings on the one hand and, on the other, theories that emphasize political-economic dynamics and elite conflict. Our time-series regression analysis suggests that while cultural-cognitive approaches best account for the initial wave of anticolonial nationalism, from 1700 to 1878, theories stressing political-economic dynamics and elite conflict explain anticolonial nationalism in the later wave, from 1879 to 1990. The analysis suggests that theories of nationalism need to be attentive to the historical specificity of their claims.