He is the author of several books on East European (particularly Polish) history and politics; his area of specialization is social change and political change in the contemporary world, in particular civil resistance to authoritarian regimes and democratic revolutions. His most recent book, Dance in Chains: Political Imprisonment in the Modern World (Oxford, 2017), examines political prisoners and imprisoning regimes from the mid-19th century, in particular in Ireland, Northern Ireland, Poland, and South Africa, as well as the men detained at Guantanamo Bay. His 2002 work, A Carnival of Revolution: Central Europe, 1989 (Princeton), has been translated into Polish, Ukrainian, Romanian, and Czech. A history of post-communism, Burdens of Freedom: Eastern Europe Since 1989 (Zed Books), was translated into Croatian and Italian.