Civil wars are the most common form of large-scale political violence. In the past thirty years, the study of civil wars has been one of the largest growing segments of the international relations field. Their causes are complex, ranging from fights over access to housing, jobs, and land or other resources, to political contests over offices, rights, and representation. Groups form, collapse, coalesce, align and realign, and then fight amongst themselves. Governments themselves change through elections, coups, military defeats, or revolutions. Understanding the origins of civil wars and their trajectories therefore demands some appreciation of the economic, political, social, cultural, and geographic order of societies. If there is one factor that best predicts why a civil war erupts, it is a prior civil war. That is why knowledge of a country's history of political violence, and associated narratives about who is to blame and why, are critical to understanding where a civil war might next occur. We now have a better understanding of the conditions under which civil wars generally emerge, how the fighting evolves, and how civil wars end. However, historical understanding—the human dimensions—remain every bit as critical. This book explores current debates on civil wars and how the reasons for fighting (and the nature of belligerents themselves) are changing.