Since the formation of modern states, bureaucracies have become the main instruments of governments for achieving developmental goals. The existence of an efficient bureaucracy is considered necessary for realizing these goals. However, in the literature of sociology, especially after the classics, the state bureaucracy has been neglected and it seems there is a kind of conceptual vacuum and confusion. This paper tries to give a critical discussion of the significant theories on the state bureaucracy and examine their reductionist attitudes, then give a clear formulation of this concept, and ultimately provide a conceptual model for its empirical study. Based on this model, the quality of the state bureaucracy in each country depends on its specific structural and institutional composition. The institutional context is the main determining factor of the quality of bureaucracy. Several variables, in the context of this institutional logic, are highlighted: the arrangement of power and the characteristics of political structure, the pattern of extraction of resources and the system of economic relations, the type of relationship between government and society, and ultimately the issue of the power and function/ agency of the elites. Each of these variables and their various dimensions is described regarding some empirical cases, and their implications for state bureaucracies are introduced.