Political and public figure. He took part in the Jewish Socialist movement from the end of the 1890s. In 1901 he was one of the founders and leaders of the Independent Jewish Workers' Party. From 1905 he was a member of Bund. He took part in the revolutions of 1905–07. In 1908–10 he was in exile in Siberia; subsequently he emigrated to Switzerland. From 1917 he was one of the leaders of Bund. In 1919 he was one of the founders of Kombund, and together with them joined the Russian Communist Party. From 1920 he was one of the leaders of the Jewish section in the Party's Central Committee. In 1921 he called for the closure of the "Gabima" theatre, on the grounds that "it served the interests of Zionist plutocrats". He was an opponent of Jewish autonomy. In 1934 he was expelled from the Communist Party for concealing his membership, at the beginning of the century, of the Independent Jewish Workers' Party, and was for a time under arrest. He was exiled to Kazakhstan. Later he worked as a photographer in Yaroslavl, changing his name in an attempt to evade the NKVD. He perished in the Stalinist repressions in 1939.