This article focuses on the complex intellectual formative process of Jose Carlos Mariategui. The aim is to discover the ideas underlying this process during his stay in Italy, identify his intellectual referents and how they influenced his political thinking. Mariategui resided in Italy from 1919 to 1923, a period which can be considered key years for the recent history of Italy as the country saw the creation of the Italian Communist Party contemporary to the rise of the Fascist movement. My methodological approach will be firstly investigating what I call the "stone age" of Mariategui, or his youthful phase characterized by his attraction towards decadence literary and a first introduction to the political and social problems of Peruvian society. Then I will analyze Mariategui's ideas and points of view on the political, intellectual, and cultural protagonists of the Italian life of the time. Finally, I will focus on the intellectual inheritance of Mariategui, taking into account five main intellectuals (Labriola, Croce, Gobetti, Gramsci and Tilgher) who -in a different way, influenced the thinking and the intellectual universe of the Peruvian Marxist.