This dissertation explains why intrastate conflicts may persist beyond the point where agreements are expected. I argue that the prolongation of certain conflicts may be tied to the character of the groups involved in them, and ultimately to the source of their finances. Calculative groups are profit-oriented; normative ones are driven primarily by the desire to demand redress for the grievances of the community to which they belong. Calculative groups may hinder the pursuit of any feasible agreement. There may be no agreements that would allow such groups to preserve themselves, and their members to continue to receive tangible benefits. Fighting remains necessary for groups to maintain control over what I call “profitable” and “strategic” territories. In the absence of viable formal agreements, these groups seek informal and local ones aimed at minimizing the costs associated with fighting, while increasing the violence against contrarian members of the organization and against civilians as a proxy, as a way to neutralize possible opposition, as a form of coercion, and as a means to financial gains. I test this argument in the Colombian environment.