Two years later, he returned to France, where he met Jean Paulhan and began working as a secretary for Gaston Gallimard.
Parain was primarily interested in the great intellectual and political movements of his time; his work focused in particular on Communism, Surrealism, and Existentialism, the failures of which he anticipated in part in some of his earlier works, such as Essai sur la misère humaine (1934) and Retour à la France (1936).
Parain supported the newspaper Le Nouveau Détective ("The New Detective"), founded by Joseph and Georges Kessel in 1928 and specialising in the evocation of miscellaneous facts.
After the Second World War, Parain worked alongside Robert Antelme and André Breton, among others, at the magazine Le 14 juillet, against Charles de Gaulle's return to power in 1958.
During the post-war period, Parain published numerous works, including a novel, Joseph (1964); a play, Noir sur blanc (1962); and various essays, De fil en aiguille (1960), France, marchande d'églises (1966), and Petite métaphysique du langage (1969).