Mironova, VeraTo be able to affect fighters behavior in Civil Wars one should understand their decision-making step by step. In this dissertation I show that after the initial decision to take up arms, which is based on individual grievances, fighters look at armed groups as institutions and make the decision to join or switch groups by comparing them based on their organizational capabilities. At the same time, when a group becomes popular (meaning its supply of fighters exceeds group demand), it is in danger of decreasing the quality of its manpower and conversion capability. In this case, adopting strict rules grounded in ideology helps the group ensure that only the most dedicated people are in its ranks. Individuals who are considering joining for reasons other than dedication to the goal of the war will think twice before joining such a group because it requires a great deal of individual sacrifices.enDissertationInternational relations