Rakovsky moved to Petrograd (the new name of Saint Petersburg) in the spring of 1917. His anti-war activism almost got him arrested; Rakovsky managed to flee in August, and was present in Stockholm for the Third Zimmerwald Conference; he remained there and, with Karl Radek, issued propaganda material in support of the Russian revolutionaries. Present in the internationalist faction of the Mensheviks, he joined the Bolsheviks in December 1917 or early 1918, after the October Revolution (although he was occasionally listed among the Old Bolsheviks). Rakovsky later stated that he had friendly relations with the Bolsheviks from early autumn 1917, when, during the attempted putsch of Lavr Kornilov, he was hidden by these in Sestroretsk.