This article investigates the determinants of armed group organization and the downstream effects of organization on civil wars. It demonstrates that the interaction between geographical and technological factors influences the types of hierarchical organizations that armed groups develop. It then argues that variations in the types of hierarchies developed by armed groups have important consequences for principal-agent relations, which in turn affect groups’ overall level of military effectiveness. Using evidence from field research conducted in Liberia and Sierra Leone, the model’s plausibility is examined in comparative case studies of four armed groups that fought in those countries from 1989–2003.

An increasing amount of development aid is targeted to areas af- fected by civil conflict; some of it in the hope that aid will reduce conflict by weakening popular support for insurgent movements. But if insurgents know that development projects will weaken their position, they have an incentive to oppose them, which may exacerbate conflict and derail projects. We formalize this intuition in a theoretical model of bargaining and conflict in the context of development projects. Our model predicts that development projects cause an increase in violent conflict if governments cannot (1) ensure the project’s success in the face of insurgent opposition and (2) credibly commit to honoring agree- ments reached before the start of the project. To test the model, we estimate the causal effect of a large development program on conflict casualties in the Philippines. Identification is based on a regression discontinuity design that exploits an arbitrary poverty threshold used to assign eligibility for the program. Consistent with the model’s predic- tions, we find that eligible municipalities suffered a substantial increase in casualties, which lasts only for the duration of the project and is split evenly between government troops and insurgents.