Political leaders make policy choices which are often hard to explain via institutions. We use the behavior of Colombian paramilitary groups as an environment to study non-institutional sources of variation in how public good provision and violence are combined to control populations. We hypothesize that a significant source of variation stems from the social preferences of the paramilitary commanders. Reciprocators adopt a strategy of offering public goods in exchange for support, but also use violence to punish those who do not reciprocate back. Reciprocity, developed via childhood socialization, is a characteristic of rural “peasants”. We develop a model which generates these hypotheses and test them using a unique dataset compiled from transitional justice documents.