Michael Mann is best known, in International Relations (IR) circles at least, for his two-volume work, The Sources of Social Power, an attempt to chart and assess the development of world-historical development from 'the beginning' to the twentieth century.(1) But Mann's career, which spans over four decades, also encompasses forays into state theory, militarism, empire, fascism, ethnic cleansing and globalisation.(2) The interview covers these various strands of Mann's work and examines some of the methodological issues involved in conducting macro-level historical sociology and interdisciplinary work.