This article investigates what motivates combatants to fight in non-conventional armed organizations. Drawing on interviews with ex-combatants from the Army of the Serbian Republic in Bosnia and Herzegovina and the Provisional Irish Republican Army, the article compares the role of nationalist ideology, coercive organizational structures, and small group solidarity in these two organizations. Our analysis indicates that coercion played a limited role in both armed forces: in the VRS coercion was relevant mostly in the recruitment phase, while in the IRA its direct impact was only discernible during armed operations. We also find that although both organizations are seen as being highly motivated by nationalist ideas, the picture is much more complex and nationalism is less present than expected. The study demonstrates that nationalism played a relatively marginal role in combatants' motivation to fight. Instead our research indicates that individualist motivations, small group solidarity, and local networks dominate.