Brendan O'Leary, an Irish and European Union citizen, is Lauder Professor of Political Science and Director of the Solomon Asch Center for the Study of Ethnopolitical Conflict at the University of Pennsylvania. A graduate of Oxford, he received his Ph.D. from the London School of Economics, where he taught from 1983 until 2003, and was professor of political science and the head of its Government Department. He has held visiting appointments at the University of Western Ontario and the University of Uppsala, and has been a Visiting Lecturer in the Social Sciences and Humanities for the Social Science and Humanities Research Council of Canada.

A leading scholar of ethnic politics and conflict, his areas of interest include power sharing systems, political violence and terrorism, nationalism, national and ethnic conflict regulation, national self-determination, constitutional design, democratization, electoral systems and human rights. His recent empirical research has focused on Northern Ireland, Kurdistan and Iraq, and political violence. He is the author and co-author, editor and co-editor of fifteen books, including: The Northern Ireland Conflict: Consociational Engagements (with John McGarry, eds, 2004, Oxford: Oxford University Press), Policing Northern Ireland: Proposals for a New Start (with John McGarry, eds, 1999, Belfast: Blackstaff Press), Explaining Northern Ireland: Broken Images (with John McGarry, 1995, Oxford: Basil Blackwell), The Politics of Antagonism: Understanding Northern Ireland (with John McGarry, Athlone), The Future of Kurdistan in Iraq (with John McGarry and Khaled Salih, eds, 2005, Philadelphia: University of Pennsylvania Press), Right-Sizing the State: The Politics of Moving Borders (with Ian S. Lustick and Tom Callaghy, eds, 2001, Oxford: Oxford University Press), Theories of the State (with Patrick Dunleavy, 1987, Palgrave-Macmillan), and The Asiatic Mode of Production (1989, Blackwell). He is also the author of more than 100 articles and book chapters, and contributes regularly to the media as commentator and author. He serves on the editorial boards of several journals, including the Journal of Ethnopolitics, Nationalism and Ethnic Politics, Nations and Nationalism, and the Journal on Ethopolitics and Minority Issues in Europe (JEMIE), and is a trustee of International Alert.

Professor O'Leary has also advised the governments of Ireland, the United Kingdom and the US on the peace process in Ireland, the United Nations and European Union on the reconstruction of Somalia, and, most recently, has been serving as an international constitutional advisor to the Kurdistan National Assembly and Kurdistan Regional Government on the Transitional Administrative Law, the Constitution of Iraq, and the Constitution of Kurdistan.