During the Civil War, the population of Jews in the city decreased because many died, and the wealthier and more educated members of the city's community emigrated. However, Leningrad Jews retained the general features of old Petersburg Jewry, such as a high level of integrity in the city's life and general Russian culture as well as many persons in the intellectual professions. Leningrad Jews were still outstanding in their traditional professions. In 1930, 36% of all Leningrad doctors and about 2/3 of the dentists were Jews. Jews occupied prominent places in Soviet journalism. They were numerous on the Bar as lawyers who had taken the place of pre-Revolutionary attorneys. In the years of the NEP, Jews were many among the proprietors of private shops, workshops and small factories.
In the mid-1920s, newcomers from Ukrainian and Byelorussian towns replenished the community. They stayed in their former professions of craftsmen or small shopkeepers. The newcomers contrasted sharply with the original Petersburg inhabitants in their appearance and poor command of Russian. However, they adapted quickly to the strange environment. Many found work in factories. Jewish workers were especially numerous at the Karl Marx Factory. But factory workers were still a minority among Leningrad Jews engaged in physical labor.
Jews were much more numerous among cooperative craftsmen, in small plants or workshops, and in government trading. Many Jewish tailors, barbers and cobblers combined their official job with illegal working at home.
Long before, the February Revolution had abolished the percentage; so tens of thousands of young Jews immediately or, as was especially common, after the Civil War, tried to get a higher education. Leningrad attracted them as a traditional center of education, science and culture. Some Jewish students chose such traditional disciplines for the Russian Jewish community as medicine, the arts or music. Others began mastering new areas - technology, the hard sciences. Those who remained in Leningrad after graduating replenished the numbers of Leningrad engineers, doctors, teachers, scientists, etc. As there was no ethnic-religious limitation and those connected with the former regime were persecuted, Jews were numerous among students and then among intellectual workers.
Hence, the main feature of Leningrad Jewry took shape: the predominance of the intellectual. Some of them were involved in the ideological service of Soviet Power; they were teachers of Marxism, Soviet and Communist functionaries. Others became scientists. It was a new occupation for Russian Jews. In the sciences with established traditions, Jews often faced hidden anti-semitism. The old Russian intelligentsia saw them as competitors. Especially well organized resistance to Jewish penetration was in mathematics. However, in physics, which had had no rich traditions in Russia before 1917, the Jews prevailed and A.F. Ioffe became the founder and the head of the Soviet Physics School.
Another notable characteristic of Leningrad Jews was their mass involvement in the arts; in cinema, music and theater especially. Such names as A. Zarkhi and I. Kheyfits, L. Trauberg and G. Kozintsev and other distinguished cinematic figures of Jewish origin were representative of Leningrad cinema of those years. In the 1930s, some representatives of the military intelligentsia appeared among Leningrad Jews; before 1917, there had been no Jewish commanders in the Russian Army. A high level of assimilation and many mixed marriages were characteristic for the intelligentsia of Jewish origin. Many Jews forgot their mother tongue and the rituals of their people. Nevertheless, in every family, there were parents or, at least, grandparents who retained Jewish traditions.