In a new publication, University of South Carolina's Chelsea Estancona, with Lucia Bird and Navin Bapat from the University of North Carolina, Chapel Hill and Kaisa Hinkkainen from the University of Leeds, studies the use of civilian self defense groups in civil wars. These groups are non-state actors that may help limit rebel groups' advancement, but also pose risks to governments' monopoly on violence. The paper, now available in International Interactions (https://www.tandfonline.com/doi/full/10.1080/03050629.2019.1554570) uses data from the Colombian civil war to evaluate where these groups are likely to emerge and participate in conflict. The paper helps us understand an increasingly common phenomenon in intrastate conflict: participation from third-party, local actors.