Cowan, MichaelHow do rebel groups cultivate devotion? Civil conflict scholars have found that when rebel groups fill their ranks with ideologically committed soldiers they are able to operate more effectively in several ways. However, the mechanisms by which rebel groups attain such devoted followers remains unexplained. I propose that insurgencies are able to cultivate devotion when they successfully deploy an ideology that balances between explanatory power and complexity. An ideology that manages to make sense of a political environment with minimal complexity provides adherents with certainty, which is a source of substantial utility. Groups that deploy maximally potent ideologies foster the emergence of a "hard core" of soldiers who depend upon the certainty afforded by the ideology and will therefore go to great lengths to act on its behalf. I articulate a theory of ideological potency and propose an associated function that expresses how much utility an individual will derive from that ideology via its certainty mechanism. I then analyze and compare the PIRA, the Viet Minh and Renamo insurgencies to demonstrate how variation in the extent to which they effectively balanced between explanatory power and complexity in their ideologies can explain variation in their capacity to attract, generate, control, and sustain devoted soldiers.enDissertationPolitical scienceCivil WarIdeologyInsurgencyIrish Republican ArmyPolitical Psychology