A review of several decades of scholarship on civil war, focusing on the answers to key questions: Why do wars begin? Who fights? How are armed groups organized? How can we end and prevent internal war? A survey of the growing body of macroeconomic and microeconomic evidence to assess the impacts of civil war on economic growth worldwide is given. This paper seeks the full answers that have eluded previous studies and charts a path forward for scholars and policymakers alike. [WP No. 166].