Societies throughout recorded history have intermittently been affected by political factionalization, a phenomenon that has frequently exercised a profoundly destabilizing effect. But the nature and origins--as opposed to the effects--of such factionalization has only rarely been broached by historians in any systematic fashion. The session is conceived as a comparative, transnational, and interdisciplinary reflection on the diverse manifestations of factionalism in times of political uncertainty and/or upheaval and the links between factions and violence. It brings together papers on widely different regions and time periods and explores common patterns and divergences in the ways factions form and develop and their impact on regimes and societies. Nicolas Tackett (History, University of California, Berkeley) will deliver a paper on "Social Networks and Factional Strife in Ninth-Century China;" Timothy Tackett (History, University of California, Irvine) will offer reflections on "Factionalism and Violence during the French Revolution;" and Michael Woldemariam (Political Science, Boston University) will speak on "Factionalism, External Alignments, and Rebel Resiliency" in the twentieth century Horn of Africa. Commentaries will be offered by the session’s chair, Carla Hesse (History, U.C. Berkeley) and by Jack Goldstone, a specialist in world history and comparative revolutions (Sociology, George Mason University). All three papers will employ digital technologies for both quantitative and qualitative analysis and draw on perspectives drawn from the social sciences. The goal is to make a contribution to a political history of factionalism that takes into account cultural and social factors, as well as issues of power. The papers and commentaries will ask questions such as: Why do factions form? What are the multiple factors (class, clan, friendship, ideology, generation, ethnicity, etc.) operative in the emergence of factional identities? And what are the circumstances under which factional divisions become toxic and lead to violence?