Why do some minorities seek affirmative action while others pursue territorial autonomy or secession, given similar conditions at the substate level? This article attempts to unpack the puzzle of minority radicalization, focusing on group claim-making as an important dynamic that has been overlooked by much of the recent quantitative literature on ethnic conflict. To address this gap, the authors introduce a new 'claims' variable, which codes the demands made by groups in the Minorities at Risk dataset for three five-year periods from 1985 to 2000. The authors examine the relationship between minority claim-making and rebellion and conclude that they are similar but distinct forms of group mobilization. Groups use claims as a means of bargaining with the center; relative power, therefore, has a critical influence on the extremity of demands that groups advance against the government. The authors test this model against alternative arguments using ordinal logit analysis and find that factors related to strategic power -including a history of autonomy, outside military support, and territorial concentrationare all positively correlated with a group's propensity to advance more extreme demands. This study shows that minorities with greater power vis-à-vis the center are more likely to both rebel and mobilize around separatist demands. However, minority rebellion -unlike separatist claims -may also be triggered by group deprivation, indicating that violent resistance may be driven by grievances as well as opportunities.* The dataset is available at