Achieving goals requires organized action. If that action is to be undertaken in the form of policy, it must stem from legitimate authority, be guided by expertise, and be coherent and consistent across cases. This is accomplished through a bureaucracy—a system of administrative units, roles, and procedures. A bureaucracy is structured to reflect relations of authority and expertise and to impose coherence and consistency. A range of factors influences how a bureaucracy is organized. The way a particular form of government apportions political authority will influence the level of formal organization and the independence given administrative units. The character of the activity to be administered will influence how administrative units relate to one another within government and how insulated or open they are to citizen involvement. Normative ways of understanding, organizing, and doing business will influence bureaucracy as well. These norms may be widespread and common to administration both inside and outside government, or they may be particular to a professional field, or particular to a form or level of government. Bureaucracies can be characterized by the extent to which they are centralized. Within one level of government, a bureaucracy may be horizontally concentrated or fragmented. Across levels of government, a bureaucracy may be vertically integrated or stratified. Structural characteristics such as shared bureaucratic norms and the degree or type of centralization found in a bureaucracy affect how decision-making happens and how efficiently policy can be implemented.