An analysis of the behavior of bureaucratic organizations in a wide variety of situations and a definition of bureaus as organizations. The study has three central axioms: (1) All social agents pursue their goals rationally and efficiently. (2) The internal structure and operations of each bureau are greatly influenced by the nature of its social functions. (3) Bureau officials are motivated at least in part by their own self-interest, even when performing official duties. Officials are divided into five types: climbers, conservers, zealots, advocates, and statesmen. The study explores how bureaus behave in a realistic world where information is costly and uncertainty exists. Facets of bureau behavior are examined extensively. Several testable hypotheses about bureau behavior under various circumstances are presented.