Why did the U.S. keep Puerto Rico as a colony after World War II? Why would a great power like the U.S. let go of a colony like the Philippines? To maintain an empire consisting of conquered territories, the conqueror has to also contend with nationalism, which can add additional “expenses” (both social and economic) to the empire in the form of counterinsurgency. In order to identify why the United States ceded the Philippines but kept Puerto Rico, I highlight two reasons. The first is distance. Objectively speaking, more resources are spent in maintaining the Philippines than Puerto Rico, due to the latter’s geographical proximity to the United States. The second is that of the difference in resources spent in counterinsurgency efforts in both colonies. Realism best explains these differences, as the theory focuses on how the interests of a state will drive its actions. The empirical analysis of this thesis will take place in two parts. The first will focus on a summary of important historical events in both the Philippines and Puerto Rico, relating to their respective times as colonies of the United States. The second part will then integrate theories of international relations in order to answer the question of “why keep Puerto Rico and not the Philippines?”