Co-founder, with Georges Franju and Jean Mitry, of the Cinematheque Francaise film archive in 1936. Starting with only 10 features, Langlois aggressively increased the Cinematheque's collection to some 60,000 films during his tenure. (As well as preserving many silent films, Langlois and his colleagues concealed and thus saved potentially controversial works from the occupying German forces during WWII). Langlois' shrine to cinema history influenced a whole generation of filmmakers, notably the future leading lights of the French New Wave.
Although the archive was subsidized by the French government from 1945, a bitter dispute erupted in 1968 between Langlois and the Ministry of Culture, headed by Andre Malraux. Impatient with Langlois' unconventional working methods, Malraux sought to remove him from control of the Cinematheque by halting governmental support. After street rallies in Paris and protests from leading international film figures, Langlois was reinstated, though the subsidy was not.