This book is About the Science of Public Administration about what we know and what we need to know about it, as well as what we can do to make science more useful to the state and society. The disarticulation between the Science of Public Administration and the administrative practice of the XXI century causes that the public administrator does not have the theoretical elements and the sufficient tools for the efficient and effective treatment of public affairs. The administration Public and its science have to be rethought not only from their inheritance, but also from their potential to provide intellectual tools and practices that increase public capacity.That is ,make a stronger,smarter and more efficient state, which can only be achieved with a solid and useful body of knowledge. From the detailed study of the State, the Science of Public Administration and its practice,facing the current needs of the governments,the autor proposes elements for its consolidation and strengthening in the XXI century.