After studying law, Costamagna joined the fascist movement in 1920 and in 1924 was appointed NationalSecretary of Technical Councils. Politically Costamagna was highly conservative and saw fascism as a transitory phase that existed only for the imposition of corporatism. On this point he had a long-running intellectual debate with Sergio Panunzio who was a strong supporter of the fascist state as an end in itself rather than just a means to economic change. He edited his own journal, Lo Stato, which he founded in 1930.