Institutional frameworks powerfully determine the goals, violence, and trajectories of identitarian movements-including secessionist movements. However, both small-N and large-N researchers disagree on the question of whether ``power-sharing'' arrangements, instead of repression, are more or less likely to mitigate threats of secessionist mobilizations by disaffected, regionally concentrated minority groups. The PS-I modeling platform was used to create a virtual country ``Beita,'' containing within it a disaffected, partially controlled, regionally concentrated minority. Drawing on constructivist identity theory to determine behaviors by individual agents in Beita, the most popular theoretical positions on this issue were tested. Data were drawn from batches of hundreds of Beita histories produced under rigorous experimental conditions. The results lend support to sophisticated interpretations of the effects of repression vs. responsive or representative types of power-sharing. Although in the short run repression works to suppress ethnopolitical mobilization, it does not effectively reduce the threat of secession. Power-sharing can be more effective, but it also tends to encourage larger minority identitarian movements.