According to one prominent claim, every opportunity for rebellion will be seized. For post–civil war societies, this implies that war inevitably recurs whenever it is feasible. While previous research has made use of probabilistic approaches to investigate this deterministic claim, this chapter employs set-theoretic methods to demonstrate that feasibility is not a sufficient condition for civil war resumption. Rather than relying on indirect proxies for feasibility, such as income level or topographic features, this chapter considers the military capabilities held by the former warring parties in 43 post–civil war dyads. The most important feasibility factor introduced here is the maintenance of separate forces throughout the post-war period. Yet, peace can also survive under such difficult circumstances. Conditions related to political inclusion that are outside of the feasibility framework help explain why peace endures. The policy recommendation is that decision-makers must also address aspects beyond feasibility.