Stern was also engaged in terms of more direct political involvement. As in much of the rest of Europe, so in Austria, the later 1920s were a period of intensifying political polarisation both among the politicians in Vienna and on the streets, and the tensions were only exacerbated by the economic austerity that arrived as part of the powerful backwash of the Wall Street Crash. In 1927 Stern was still a member of the Social Democratic Party, although he was regarded by many, including himself, as part of the party's extreme left-wing. He participated in the 1927 "July revolt", teaming up with his comrade Ernst Fischer with whom he worked closely. Later, probably during the early or middle 1930s, there would be a spectacular falling out between the two men. Although for many years, out of respect for party discipline, Stern set aside or concealed his dislike of his former partner in activist politics, it is clear from a letter that he wrote in 1968 to Eduard Rabofsky (1911-1994), that under the surface, Stern's mistrust and loathing of Fischer persisted.