The science administration, as a distinct branch of the science, which researches the public administration in its complex events, was established during the time as a result of focusing on improving the public administration. The research of the public administration comprises and expands some traditions of thinking and writing, materialized in theoretical and empirical studies concerning the activities developed by many public administrative bodies from the world, concerning governmental structures, politico-administrative planning, the improvement of the activities and the administrative behavior. The American school of research in the domain of public administration had a special role in the delineation of the administrative science as an independent science. Various approaches of the administrative phenomenon, elaborated by the American researchers, are universal and in the same time specific by the fact that they exceeded the approaches of legal nature and were achieved in a federal context of government.