For decades after democratization, discussions about the state was concentrated on the raison d'être and the new public role of the state and the way of checking the abuse of state power. This paper is an attempt to theoretically clarify the concept of ‘state capacity’ as a substantial condition to realize the Staatsideale embodied through such social discussions. Recently, studies on state capacity, government capacity, good governance, and the quality of government have been rapidly increasing, but they often do not inherit the huge theoretical insights of the sociological literature that has had a great impact on this subject area. On the contrary, they tend to narrow the concept of state capacity to the administrative executive capacity of the government and simplify the complex relations between various dimensions of state capacity into a numerical sum of index values. To overcome such limitations, this paper examines the core sociological literature that provided an immediate basis for the recent studies of state capacity, and tries to amplify the theoretical implications condensed in this concept. The argument of this paper is that state capacity is not just a formal concept to measure certain executive features of the government, but a theoretical concept that refers to the active ability of the state, which claims authority and legitimacy as the only public organization that concentrates on the issues of the political community, to territorialize, institutionally regulate, and affect the behavior and relationship of social groups. In addition, the paper argues that because the different dimensions of the state capacity-the coercive, administrative, extractive, legal, distributive and productive capacities- have their own institutional legacies and dynamics of change, it only serves to distort or obscure the perception of reality to judge the general state capacity of a nation as strong or weak. Instead, we should make the concrete question of ‘which kind of state capacity?’ and ‘state capacity for what and whom?’ lead our research. Through such theoretical reflections, we would be able to better elaborate on the substantial issues, including the institutional arrangement of democratic and authoritarian state capacities, the conditions of state capacity required for more universalistic welfare state, and the nature of national competence that alleviates or deepens inequality.