I am Professor and Chair of the Political Science Department at The University of Pennsylvania. I write on conflict processes with a focus on civil wars and inter-ethnic conflict in the fields of international relations and comparative politics. Published work in these areas has appeared in the American Political Science Review, International Organization, World Politics, The Journal of Conflict Resolution, Perspectives on Politics, and other journals. I co-authored Making War and Building Peace (Princeton University Press, 2006), the first book to analyze the impact of United Nations peace operations in post-conflict transitions; and Breaking the Conflict Trap: Civil War and Development Policy, one of the first quantitative studies of the causes of civil war around the world. In a two-volume book project (Understanding Civil War: Evidence and Analysis) I developed a nested, mixed-methods research design for the analysis of causes of civil war onset. I currently direct Penn’s Identity & Conflict Lab, an inter-disciplinary group working on a broad range of topics related to inter-group conflict. The PIC Lab produces cutting-edge research on the causes of inter-group conflict, on civil war and separatism, on the effects of external intervention on ethnic polarization; the stability of power-sharing after ethno-sectarian war; and other mechanisms to reduce or overcome inter-group conflict. We study these questions with attention to the connection between identity politics and conflict processes and several ongoing projects address conflicts involving immigrants and displaced populations. The Lab is interested in studying the long-term legacies of violence exposure; the sources of ethnic and national identification; and the effects of integrative institutions in overcoming ethno-sectarian conflict. This research is producing new insights on ways to integrate political science theories of international conflict and cooperation with social-psychological theories of identity-based conflict.