The Science of the Modern Age carried out the Librarianship and the Management as particular scientific disciplines. The beginning of the 21st Century gives us a suitable historical distance to purview the principal streams of the development of both disciplines, and the Synthetically Structure of the Science of the Post-Modern age in practice, and defines the Management in Libraries as series of mutuality linked continued activities regarding Planning, Organization, Conducting and Control, that are pursued through work with people and with the help of Resources of the Library, but they are directed to realize their missions in the Modern World.