The territorial state today the unit par excellence in the international system, but this has not always been the case. Rival forms of organization, such as empires, city states, trade confederations and religious associations, were eventually replaced by the territorial state as we today know it. We argue the that the peak of this state-building process occurred in the "long 19th century" (around 1789-1914), and that this coincided with a rapid expansion of the scope and functions of the state. Three overall research themes build the core of this research program: (1) How did the different dimensions of state-building, including internal and external sovereignty, revenue extraction, professionalization of the bureaucracy and the development of infrastructural capacity, evolve and interact during this time period? What actors and organized interests supported or put up resistance to the process? (2) How were the dimensions of state-building affected by geopolitical competition, warfare and the diffusion of novel political technologies? And (3) What were the consequences for the international system, both with respect to the type of state that emerged and what entities were granted membership in the state system? The program will be carried out at the department of political science, Lund University, and aims at bridging the gaps between comparative politics and IR and between the study of political thought and positive empirical political science.