Hyslop’s article criticizes Julian Go’s approach to the historical analysis of empires. It views his work as an example of comparative historical sociology and contrasts it with the methods of transnational historians. While both schools constitute valid research directions, the rise of transnational history has made the work of comparativists more complex, in ways Go does not suffi ciently recognize. Especially, it highlights the diffi culty of drawing lines between the political units that are to be compared. While the article appreciates the elegance of Go’s comparison of the trajectories of British and American imperialism, it points to several flaws in his analysis. In particular the article criticizes Go for not recognizing the historical interpenetration of the British and American empires. It also suggests that his work reflects a tendency in comparativist work toward a structuralist dismissal of issues of agency and culture. Go downplays the role of the internal politics of metropolitan societies in shaping imperialism, Hyslop argues, and sees colonial societies as more united in their resistance to imperialism than they were in reality. Hyslop’scritique of Go draws on Michael Mann’s analysis of the multiple forms of social power.