The article analyzes the impact of private military companies (PMCs) on the duration of civil wars in Africa from 1990 to 2008. We develop an "opportunity structure" theory to argue that while PMCs are profit-oriented entities, the prevalent opportunities in conflicts will determine how they behave in war zones. Empirical findings for civil wars with at least 1,000 battle deaths show that as level of competition among government-hired PMCs increases, they are more likely to deliver optimal services and help bring an end to violence. In the absence of competition, the prevalent structure creates opportunities for PMCs to underperform in order to maximize profits by staying in conflicts longer. The authors also show that swift cessation of hostilities could benefit those profit-seeking PMCs that are compensated with contracts to extract natural resources because resource extraction generates more wealth in peace time. In such cases, the prevalent opportunities in conflict create an incentive for companies to deliver optimal service and terminate hostilities.