The goal of this essay is to examine through which parameters was accomplished the transplant of ideas and notions that permeated Pasquale Stanislao Mancini’s (1817-1888) thought on the Principle of Nationality within Brazilian, Uruguayan and Argentinian legal culture along the twentieth century, and how its incision in the cultural identity of both countries occurred. For this purpose, discourses Argentinian and Brazilian books about International Law and Constitutional Law will be analyzed. It will be also contemplated, on this aim, the impact in the Brazilian, Uruguayan and Argentinian legal culture derived from the reception of ideas like ‘race’, ‘language’ and ‘spontaneous consciousness’. Those concepts were employed by Mancini as a basis on his master lecture at the University of Turin in 1851. Finally, it will be pointed out the main differences between the approaches of these legal cultures.