The domination among peoples is a historical constant. But the begining of the reference to this phenomenon as "colonization" or "colonialism" is usually situated in the modern age. It is not fortuitous such a temporal frame. The notion of "the State", fundamental for the understanding of the concept of colonialism, was gradually taking shape throughout the said historical period. From the sixteenth century, the subjugation of those cultures considered inferior was understood within the same process of unification of territories and concentration of monarchical power. The territories conquered in Overseas zone represented the territorial prolongation of the newly unified kingdoms in the metropolises, and the peoples of these new occupied territories were subjected to a process of cultural transformation that, as it was said, brought them from barbarism to humanity, that is, to civilization. In this early period of the birth of colonialism, the protagonists were Portugal and Spain, two kingdoms whose expansion towards both Africa and America not only caused border conflicts between both christian kingdoms, but will also faced them against the conquered peoples. From the resolution of these border conflicts through the issuing of property titles (bulls) by the popes, and from the resolution of the debate on the nature of the conquered peoples or on the treatment that had to be given to them, were established those principles that, according to scholars, are considered the Sanctus santorum of colonialism. Despite the defence deployed by the dominican friars (mainly Bartolomé de Las Casas and Francisco de Vitoria) in favour of the conquered peoples, and despite the Holy See recognized the humanity and the freedom of these peoples (The Bull Sublimis Deus, the June 2nd, 1537), the superiority of the euro-western culture over that of the conquered peoples was affirmed. Such bases, that is, the application of the notion of res nullius to the conquered territories, the definition of their peoples from their paganism and barbarism, and the "moral duty" of Europe to lead them to the light of the true faith and civilization, despite being frankly contrary to the universalism that characterized the iusnaturalist conception of principles such as equality and freedom, were perfecly matched not only with the Bill of Rights emanating from the liberal revolutions, the American and French ones, but also with the whole of liberal constitutionalism. In other words, from this perfect conjunction between the slavery (or colonialism) and the natural rights declared by american and french revolucionaries, only two conclusions can be drawn: either the enslaves and colonizeds were not included within the concepts of "men" or "citizen" used by the said liberal bills of rights, or simply both categories was to be interpretated according to cultural-racial factors. The beginning of the 20th century implied the opening of a new stage in the evolution of human rights theory. With the Weimar Constitution, It started a process of redefinition of the principles of the liberal constitutionalism. The Weimar Charter initiated the overcoming the abstraction that separated the guarantees declared in liberal constitutions from the reality of the holders of those legal guarantees. As it would be then said in the Weimar Constituent Assambly, with this text, both the liberal rights and the new social guarantees went from being "mere declamations of rights" to being ""true declarations of rights". In the first German democracy, concepts such as "popular sovereignty" of "citizen" acquired an integrating meaning that transcended all the racial, sexist or economic connotations that marked them in liberal constitutionalism. And what is more, the Weimar Constitution integrated the new social class, the workers, and affirmed the humanization of working conditions as an indispensable step for their complete integration into the productive system of liberal states. But, as is well known, the growth of Western industries was due not only to the work of european labourers, but mainly to the efforts of the enslaved and colonized peoples in the overseas territories. The question of the integration of these peoples remained suspended in the Weimar Constitution. It is true that the Weimar Constituent, as deduced from the article 6.2 of its work (the exclusive competence of the Reich over the Colonies) never imagined the liberation of its protectorates in Africa and Oceania. But this firm colonialist will should not lead us to automatically conclude that the first german democracy, like the liberal ones, would have ended up denying constitutional protection to the colnonized peoples. It is highly logical and probable to believe that the new weimarian social constitutionalism, in the same vein of the liberal constitutionalism, could have ended up adopting such an exclusion of Overseas. But it is also probable, although minimally, that the german democracy could have extended its constitutional guarantee to its colonies. The materialization of any of both options could only be observed from the same colonial experience, reality from which Germany was excluded according to the provisions of the Treaty of Versailles. But if from the german experience it is impossible to affirm the ambiguous character of the new social constitutionalism with respect to the colonized peoples, it is not, nevertheless, impossible to affirm this ambivalence from the colonial experience of Constitution of the Spanish Second Republic, faithful tributary of the speech and the new weimarian values. With the analysis of the reforms approved by the Republic in the Spanish Guinea, the present thesis tries to imagine, from the perspective of spanish republicanism, how the new weimar socialism could transform the reality or the rights of the so-called colonized.