Conclusions about the potential for peace via power-sharing are mixed. For some, power-sharing does little to overcome the commitment problem characterizing a transition from conflict, while others argue that such concessions provide signals of parties’ willingness to incur costs. This article develops and tests a new theory, aiming to shed light on the mechanisms through which power-sharing bargains help to overcome the commitment problem. I argue that government parties tend to hold an electoral and military advantage, which heightens incentives for rebel leaders to defect from a settlement prior to conceding their capacity to use violence. Where settlements provide discrete guarantees that offset the risks of electoral defeat and the co-optation of forces, these incentives for pre-emptive defection should be mitigated. I offer a novel disaggregation of provisional power-sharing subtypes, distinguishing between long-term and short-term arrangements. The analysis rests on an original, cross-national dataset of government-and-rebel dyads to negotiated settlements signed between 1975 and 2015 (N = 168). The logistic regression results clearly indicate that power-sharing settlements stipulating ‘consociational’-style reforms are significantly more likely to resolve conflict between settlement dyads, all else equal. Meanwhile, standard conceptualizations of power-sharing, which include transitional coalitions and troop integration, appear unlikely to secure rebel commitment beyond the transition period, which helps to explain the contradictory findings in existing research.

While it is widely accepted that negotiated settlements are prone to breakdown, our understanding of the processes through which signatories defect lacks precision. A growing qualitative literature recognizes the potential for rebel group fluidity, yet the conflict field’s converging reliance on dyadic data obscures pathways of defection that result in splintering or merger in quantitative studies. An in-depth case study of a failed peace process in Uganda—which is misclassified in the extant data—helps to illustrate the ways in which excluded groups can lower the opportunity cost of defection for splintering factions, resulting in a strategic alliance. I test the generalizability of this argument against the full sample of rebel parties to settlements in Sub-Saharan Africa (1975–2015) using a large-N qualitative analysis of causal process observations (CPOs). The aggregated results provide strong evidence that the defection-by-alliance pathway is much more prevalent than previously recognized, accounting for more than one-third of all defections in the sample. Where settlements create shared incentives for stakeholders inside and outside the peace process to spoil, rebel elites appear more willing to bear the costs of an alliance with a rival, rather than surrendering under adverse conditions.

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