Civil wars are one of the most pressing problems facing the world. Common approaches such as mediation, intervention, and peacekeeping have produced some results in managing ongoing civil wars, but they fall short in preventing civil wars in the first place. This book argues for considering civil wars from a developmental perspective to identify steps to assure that nascent, low-level armed conflicts do not escalate to full-scale civil wars. We show that highly structured intergovernmental organizations (IGOs, e.g. the World Bank or IMF) are particularly well positioned to engage in civil war prevention. Such organizations have both an enduring self-interest in member-state peace and stability and potent (economic) tools to incentivize peaceful conflict resolution. The book advances the hypothesis that countries that belong to a larger number of highly structured IGOs face a significantly lower risk that emerging low-level armed conflicts on their territories will escalate to full-scale civil wars. Systematic analyses of over 260 low-level armed conflicts that have occurred around the globe since World War II provide consistent and robust support for this hypothesis. The impact of a greater number of memberships in highly structured IGOs is substantial, cutting the risk of escalation by over one-half. Case evidence from Indonesia’s East Timor conflict, Ivory Coast’s post-2010 election crisis, and from the early stages of the conflict in Syria in 2011 provide additional evidence that memberships in highly structured IGOs are indeed key to understanding why some low-level armed conflicts escalate to civil wars and others do not.