This research investigates the films of Alberto Cavalcanti, his heritage and role as an aesesthetic pioneer in the post world war II era that preceded modern cinema. There are two main characteristics that indicate that his role in the neorrealistc movement was much more important than has previously been considered. First of all the intense social and poetic aspects of his work, primarily in his French phase, in films such as Rien que les heures (1926), and later more explicitly in English documentaries such as Coalface (1935). Cavalcanti dissolved the borders between documentary and fiction starting with his production of Rien que les heures and continuing through his entire involvement with General Post Office Film Unit. Beginning with these premises an analysis of the roots of modern cinema, historically credited to the Italian neo realism movement will be possible.