The prevalence of cooperation among appropriators in common-pool resources contradicts the predictions of the theory of collective action. Understanding the factors that affect the propensity for appropriators to cooperate will yield insights into the role of institutions and social norms in managing resources. An evolutionary game theory model is constructed to show the emergence and stability of a cooperative equilibrium subject to initial conditions. A logit regression model is used to determine the effect social, institutional, and physical variables have on the probability of a cooperative equilibrium emerging in irrigation systems in Nepal. The system location and type of management structure are found to affect the likelihood of cooperation and efficient use of the resource.