Michael Mann is a central figure in contemporary sociology. His analysis of how the four sources of social power - ideological, economic, military and political - have shaped world history is a major contribution to social science. In this volume, distinguished scholars assess Mann's work, focusing on his final two volumes of Sources of Social Power, which deal with the twentieth and twenty-first centuries. They tackle some of the major themes in Mann's work including globalisation, American empire and the recent financial crisis. They also question his stance on some perennial topics in sociology: is the trajectory of American society 'exceptional'? How is military power different from the other sources of power? What is the role of agency and ideology in social change? How do the relations between states affect domestic social development? Global Powers will provoke debate among all those interested in understanding the next phase of globalisation.