Following his refusal to swear loyalty to the Fascist regime, Lionello Venturi left his teaching post at the University of Turin and chose exile. In this article I try to reconstruct the activity of this art historian in the years spent in France (1932-39) and the U.S.A (1939-45). Studying the private letters to and from his father Adolfo (Archivio Venturi, Biblioteca della Scuola Normale Superiore, Pisa) and Berenson (Archives Berenson, The Harvard University Center for Italian Renaissance Studies, Villa I Tatti, Florence) I have been able to follow traces left by the scholar during the numerous moves he made as part of his intellectual wanderings, stressing the years dedicated to the elaboration of the History of Art Criticism (1936) the great monograph on Cezanne (1936) and the collection of documents published with the title Les Archives de l'Impressionisme (1939). It was in those same years that the political police kept watch on the anti-fascist activity of the scholar. The materials preserved in the Archivio Centrale dello Stato di Roma allowed me to follow up this little known aspect of the cultural commitment of Venturi, a goal he doggedly pursued till his return to Italy in February 1945.