||Civil-military conditions have changed considerably in the Southern Cone since the transition to democracy. Militaries are not necessarily confined to the external sphere, as conventional wisdom suggests they should be--yet many Latin American militaries remain under the control of their civilian governments. What determines mission types, if not the degree of civilian control? How can we know how "democratic" these missions are if they range so dramatically? This thesis addresses these questions by undertaking a project to determine the indicators of internal and external mission types in a comparative case study of Argentina, Brazil, and Chile. These countries share a similar militaristic past, yet they prioritize different sets of missions today. This thesis explains the variation by completing the imperfect picture provided by existing explanations of civilian control. Furthermore, it provides a comprehensive model that explains how civil-military conditions and the security environment interact to determine military mission types.