A few months after its founding, it was a concern for the Communist Party of Chile to establish fascism in their country. Communist antifascism was a discourse that was built early and that correlated national and international factors. In this article, we explain the historical development of this process and its impact on the political practice of the party from its foundation to the inflection of "class vs. class" politics in 1934. We argue that the construction of communist antifascism was divided into two phases. The first was marked by the similarities and correspondences that certain actors and situations had with European fascism, which generated a wide range of receptions around the relationship between violence, fascism and capitalism, which finally allowed them to identify fascist methods in Chile. Thus, the second phase was devoted to the construction of an identity and strategic discourse in a defensive code against the fascist imprint of the governments and regimes of the turn of the first part of the 1930's.