Why do territorial disputes become more difficult to resolve over time? Why are states often unable to resolve long-standing territorial disputes over land that is of little strategic or economic value? One explanation for territorial dispute entrenchment draws on changes in dispute perception. Specifically, as territorial disputes mature they undergo processes that increase the integrity of the disputed territory, clarify the definition of the territory's boundaries, and make it more difficult to find substitutes for the territory. Territorial dispute resolution is both stochastic and exogenous to the entrenchment process and thus impossible to predict. It is possible, however, to forecast ex ante the degree to which young territorial disputes are likely to resist resolution efforts in the future based on two variables: perceptions of a territory's integrity, boundaries, and value at the outset of the dispute, and physical constraints on expansion and settlement into the territory.