The proposal of this dissertation consists in a review of the federalism, by searching, from a triple perspective, its essence, in others words, the nucleus to be preserved for the building of democracy and fundamental rights. In the first perspective - a static view -, the essence of the phenomenon is taken from the identification of its structural elements and characteristics that make it singular. The federalism is understood as a mechanism of control against despotism, allowing territorial distribution of the state political power between selfgovernment entities, that are united by coordinate and cooperative relationships, aiming common objectives. The second perspective reflects the dynamic essence of the federal State, recognizing its flexibility and its capacity to adapt to the different social, political, economic and ethnic realities, which is revealed by its historical route and by the description of the United State case, since its origins until the current outlines determined by the Supreme Court. The third perspective examines the essence of federalism under the prism of values and juridical principles, in order to identify federal state´s inspiring and structural principles. Introduced the federalism under this triple perspective, the study indicates, at its end, the key for conciliating the essence simultaneously static and dynamic of the federalism, through the harmonization of the federated entities´ self-government with the national integration, in a way to assure the permanent statement of democracy and fundamental rights and the integrity of the union.