This course explains ethnic conflict, focusing on its most violent form, civil war. There have been more than 170 civil wars and many more episodes of lower-level armed conflict around the world since 1945. Most of these conflicts have been fought along ethnic lines. Antipathies and competition between ethnic groups are a constant feature of human history. Across societies, there is evidence of in-group bias and out-group prejudice in human behavior. Some theorists argue that people are hard-wired to dislike –and even fight against— members of ethnic out-groups. But large-scale ethnic violence is relatively rare. Under what conditions does ethnic conflict become violent and when does that violence rise to the level of civil war? What interventions are effective in ending these wars and returning countries to peace? Is ethnic conflict rooted in economic factors, such as poverty, growth decline, commodity price shocks, or dependence on mineral wealth? Or is it due to political reasons, such as repression, authoritarianism, or political exclusion of minority groups? This course addresses these questions from an inter-disciplinary perspective, drawing on quantitative political science, history, social psychology, and behavioral economics. By the end of the course, students should be able to discuss these questions with reference to ongoing cases of civil war in Iraq, Afghanistan, and Syria as well as historical cases such as Bosnia and Rwanda.