Trotsky was born of Jewish parents in the S Ukraine. His father, a prosperous farmer, sent him to Odessa, where he became an outstanding student in a German secondary school. He early became a populist, and he began to be attracted to Marxism in late 1896. In 1898 he was arrested for the first of many times. Exiled to Siberia in 1900, he escaped in 1902, using a forged passport under the name of Trotsky, the head jailer of the Odessa prison in which he had earlier been held.
He went to London and collaborated with Vladimir Ilyich Lenin on the revolutionary journal Iskra [spark]. After the split (1903) in the Russian Social Democratic party he was for a short time a leading Menshevik spokesman, but he later established an independent course, wavering for years between Bolshevism and Menshevism.
Returning to Russia in 1905, Trotsky became chairman of the short-lived St. Petersburg soviet and was arrested during its last meeting. While in prison, he developed his theory of permanent revolution; he declared that in Russia a bourgeois and a socialist revolution would be combined and that a proletarian revolution would then spread throughout the world. Banished again to Siberia, he escaped to Vienna, where he worked (1907–14) as a journalist. At the outbreak of World War I, he went to Switzerland and then to Paris, where he was active in pacifist and radical propaganda. Expelled from France, he moved (Jan., 1917) to New York City, where he edited, with Nikolai Ivanovich Bukharin and Aleksandra Mikhaylovna Kollontai, the paper Novy Mir [new world].
He returned (May, 1917) to Russia after the overthrow of Nicholas II, and, by July, 1917, was a member of the Bolshevik party, taking part with Lenin in the unsuccessful Bolshevik uprising of that month. He was imprisoned by the Aleksandr Kerensky government but was released in September. He was one of the chief organizers of the October Revolution (see Russian Revolution), which brought the Bolsheviks to power.