One of the most fundamental principles underpinning the post-World War II order, on which there is a broad and long-held consensus, is that once admitted into the club of universally recognized states, a political entity’s territory and borders become sacred. The phenomenon of the “contested state,” however, stubbornly challenges this sacred consensus, by suggesting that the current membership in and territorial configuration of the international society may not be entirely fixed. With three standalone substantive chapters, this thesis investigates three different aspects of contested states’ relationship with the existing society of states. In Chapter 1, I attempt to make sense of the existence of these entities alongside other actors in the international system.  By employing an ontological approach, I argue that a constellation of four dimensions constitutes a  contested state as an independent non-UN member state, over which another State lays claim. My approach not only establishes these entities more clearly as a separate analytical category in world politics, worthy of detailed study, but also specifies these entities’ distinct behavior when compared to other actors populating the same international system. Departing from the empirical reality that more than half of the thirty contested states have already died, Chapter 2 investigates the conditions under which contested states survive in the post-1945 international order. By employing an original time-series dataset and applying a comparative configurational analysis of the universe of cases of contested states, I show that three pathways to survival sufficiently capture the patterns underlying the persistence of these entities. The Chapter shows that, while external support is not a necessary condition for contested state survival, what happens outside a contested state’s own “domestic” realm, nevertheless, plays a crucial role in keeping these entities alive. The findings of this Chapter unearth a contradiction that exists between the prerogatives of territorial integrity and the aims for peace and stability of the post-WWII international legal and normative order. Chapter 3 conducts a critical analysis of the nature and effect of contested states’ struggle for recognition by focusing on Palestine and Kosovo. While seeking recognition and maintaining the hope of eventual membership in the society of states is an understandable objective, I argue that for contested states, recognition has a price. The post-WWII international legal and normative order has presented contested states with a trade-off. In seeking to achieve universal international recognition, contested states must curb their claims to self-determination and sacrifice some of the elements of empirical statehood they have managed to establish. Taken together, these chapters make a set of empirical, methodological, and theoretical contributions, not only for the study of contested states but also for the general discipline of IR.