This article examines the impact of the ethnic exclusiveness of regimes on commitment problems and hence on civil conflict duration. It argues that members of privileged in-groups in highly exclusive regimes can be trapped into compliance with the regime. Ethnic exclusion helps to construct privileged-group members as regime loyalists. They therefore fear rebel reprisals even if they surrender or defect, and hence persist in fighting. The article finds in particular that privileged-group members mistrust even rebels who mobilize on a non-ethnic agenda. Severe ethnic exclusion induces members of privileged groups to regard rebel reassurances, including non-ethnic aims, as suspect. Exclusion therefore induces privileged-group cohesion, an effect more resistant to rebel reassurances than previously recognized. A case study of the Syrian civil war shows this dynamic at a micro level, and a cross-national statistical analysis gives partial evidence that it lengthens civil conflicts on a large scale. This article examines whether, and how, ethnic politics makes civil conflicts long and intractable. 1 It studies the impact of regime ethnic 2 exclusiveness on credible commitments and hence on civil war duration. It argues that ethnic exclusion by the regime undermines the trust in rebel reassurances that members of privileged groups might have. Ethnic exclusion puts privileged groups in a loyalty trap: while some privileged-group members enjoy greater access to