Educated in Kishinev. Graduated from Heidelberg University in law in 1911.
Arrested for revolutionary activity in Nikolaev in
1904, exiled to Turukhansk, Siberia in 1905. Fled abroad in 1907. Took part in the Zimmerwald conference during World War I. Returned to Russia in 1917. Member of Petrograd Soviet.
Supported the Bolsheviks in October 1917. After the expulsion of the left wing from the SR Party (for collusion with the Bolsheviks), became leader of the left SRs. Joined the coalition government with the Bolsheviks, December 1917.
After the ratification of the peace treaties of Brest-Litovsk by the 4th Congress of Soviets, March 1918, the left-wing SRs left the coalition. Became a radical critic of Lenin, took part in the 3rd Congress of the left SRs, June 28-July 1, 1918. Trotsky demanded his execution (together with his group) as saboteurs of the Brest-Litovsk treaties.
After the assassination of the German Ambassador Mirbach, became leader of the left SRs’ uprising in Moscow, July 1918, suppressed by the Latvian Cheka detachments of Vatsietis. Went underground, but continued to lead the left SRs. Arrested in January 1920 in Moscow.
Released for cooperating with the government by writing a series of articles, urging support for the Bolsheviks in the war with Poland. Re-arrested in February 1921 with all the other left SR leaders. In prison, 1921-1923, and arrested and imprisoned on several subsequent occasions.
All the left SRs were arrested again, 6 February 1937. Prosecution witness at the Bukharin trial, yet sentenced to death and executed.