Following a brief stay in Demark in 1934, Chakhotin took up residence in France where he obtained a succession of posts in the Collège de France, the "Institut Prophylactique de Paris," the Hôpital Léopold Bellan, and the "Institut de biologie physico-chimique"). During most of his time in France his material situation was precarious. Politically he became involved with the radical wing of the SFIO, in particular with Marceau Pivert and Jean Zyromsky and the Jeunesse Socialiste where he established himself as an authority in anti-fascist propaganda. By 1936 he had became an assistant to Marceau Pivert, eventual Secretary of the Federation of the Seine of the SFIO and head of propaganda for the SFIO at the outset of the Popular Front government. The Three Arrows symbol became current in the propaganda of the SFIO and of Pivert's group, the "Gauche Révolutionaire". In 1939, his key work was published in Paris. Shortly after the release, it was removed from bookshops by the French police, and was formally banned, with copies being destroyed when the Germans occupied France in 1940. In June 1941, following the German invasion of the USSR, Chakhotin was arrested and held in an internment camp in Compiègne. He was released on 23 January 1942, thanks to a character reference provided by four distinguished German scientists. The prison authorities had been unaware of his authorship of "Le viol des foules." In early 1944, Chakhotin was invited to assist the under the Nobel Prize-winning medical scientist Alexis Carrel in constructing a scientific data base, and to advise on the application of the biological sciences to the social sciences. His monthly fee of 5,000 francs provided an adequate income after years of penury. However, on 8 March 1944 he resigned from the following allegations of Carrel's association with the Pétain regime.