The incidence of international conflict has been analyzed extensively through the framework of opportunity and willingness. Opportunity has mainly been operationalized as physical proximity. Willingness has been measured in a number of ways, and remains a somewhat more elusive concept. Several scholars have called for boundary length to represent opportunity. Heeding such calls, Harvey Starr has used GIS methods to generate boundary length for 1993 and has found it to be associated with increased propensity to conflict. A number of his measures of willingness were not. Using a new and much more extensive dataset on boundary length for the entire Correlates of War period, this article finds very different results. We study the relationship with shared rivers and water scarcity as measures of neomalthusian factors in willingness over a 110-year period. The results indicate that the neomalthusian factors are significant although not dramatic in their effects. Boundary length, while significantly associated with conflict in a bivariate analysis, fades into insignificance when the neomalthusian willingness measures are introduced.