Freudo-Marxism is usually understood in two ways. In a broad, vague and diffuse sense, it encompasses all efforts of synthesis between Marxism and psychoanalysis. In a strict sense, which we will choose here, it only includes the efforts made in the interwar period, between the 1920s and 1930s, when attempts were made to systematically integrate the Marxist and Freudian traditions under an assumption of profound affinity and complementarity between them. Freudo-Marxism in the strict sense includes works by authors as diverse as the great Marxists Leon Trotsky, Antonio Gramsci and José Carlos Mariátegui, the Austro-German psychoanalysts Siegfried Bernfeld, Wilhelm Reich and Otto Fenichel, the Soviets Vera Schmidt and Aleksandr Luria, the Frankfurters Max Horkheimer and Erich Fromm, the surrealists André Breton, René Crevel and Tristan Tzara in France, Karel Teige in Czechoslovakia or Xavier Abril and Elias Piterbarg in Latin America, the Freudian critics of Marxism Henri De Man and Max Eastman, and some unclassifiable ones like the Brazilian Oswald de Andrade, the Hungarian Attila József and the French Jean Audard. Many of the exponents of Freudo-Marxism have already fallen into oblivion. However, as we will see, they all retain their relevance and their great subversive potential. This is why they can still give us the twelve lessons that we will summarize here.