In the winter after he left the Seminary, Stalin obtained a job as an accountant at the Tiflis Observatory. This position was to be the only regular employment he ever had, and functioned as little more than a front for his activities as a Marxist: many of his co-workers belonged to the Social Democratic Party, and the observatory provided an ideal meeting place and hideaway for forbidden literature. He worked there for more than a year, during which time he made his first political speech--addressing a crowd of nearly 200 workers on April 23, 1900--and was given control over disseminating Marxist propaganda among railway workers. At this point, he took the name of "Koba," after a famous Georgian bandit from his childhood reading. In March of 1901, however, the police raided the observatory, and although Stalin escaped, he lost his job and became a professional revolutionary, as he would remain until the Revolution.
After the observatory raid he continued to work among the Tiflis Social Democrats for another year, writing articles and organizing rallies, but he soon managed to alienate most of his superiors--not the last time that Stalin would antagonize those around him!--and was expelled from the local branch of the party. Undeterred, he simply moved to another city, joining the Social Democrats in the Georgian port of Batum, where, on March 9, 1902, the police fired into a crowd of marchers, killing fifteen and wounding fifty-four. Official Soviet history would later give Stalin credit for organizing this demonstration; and although his exact role in it was unclear, he did receive imprisonment for his involvement--in November 1903 he was sent to the village of Novaya Uda. But after only a month of exile, Stalin escaped and returned to Georgia. This was by no means a difficult feat; under the Tsars, security in Siberia was notoriously lax. Exile was reasonably comfortable, and escape relatively easy. The contrast with the conditions of political exiles under Stalin's regime is remarkable.
While Stalin was still in prison, the Social Democrats held their Second Congress in London and Brussels (Marxist meetings were illegal in Russia). It was there that the famous split in the party emerged, between the so-called Bolshevik ("majority") and Menshevik ("minority") wings. Both groups were radical, but they divided over whether party membership should be confined to a class of professional revolutionaries (as the Bolsheviks thought) or whether it could extend to anyone who supported the party's program (as the Mensheviks thought). In practical terms, this divide was critical, since the Mensheviks would come to emphasize a broad, popular revolution, while the Bolsheviks would advocate (and carry out) a violent seizure of power by a small elite group. The "majority" and "minority" terms notwithstanding, the Mensheviks were the stronger wing in the years before World War I--but the Bolsheviks drew strength from their leader Vladimir Lenin, a celebrated Marxist writer and agitator, then in exile in western Europe.
Upon his escape from Siberia, Stalin naturally gravitated toward Lenin and Bolshevism, but he failed to distinguish himself in the next few years even within the tiny Bolshevik group in Georgia, gaining a reputation mainly for his extremism and abusive manner in party meetings. In 1905, meanwhile, after suffering defeat at the hands of the Japanese, the Russian Empire was rocked by a series of protests, beginning with "Bloody Sunday," when peaceful demonstrators were gunned down before the Tsar's Winter Palace in St. Petersburg, and continuing with general strikes that paralyzed the Empire. This 1905 Revolution very nearly toppled the ruling family (the Romanovs), but the monarchy was saved at the last minute when Tsar Nicholas II agreed to the formation of an elected assembly, the "Duma," with the power to pass legislation.
But Stalin's role in these disturbances was minimal; he gave speeches and wrote articles, but he was far from the action, and was overshadowed by his great rival Leon Trotsky, then a Menshevik, who organized strikes in St. Petersburg. Indeed, Stalin's chief accomplishment in this turbulent year was to get married, to his first wife, Yekaterina Svanidze, about whom we know little; she bore Stalin his first son, Yakov, in 1907, but she died that same year, and the young Yakov was left in Georgia to be raised by an aunt and uncle.
In the years after 1905, the radicals retreated underground again. Police persecution thinned the ranks of the Georgian Bolsheviks, and Stalin, still under the name of "Koba," rose to leadership. He attended a number of party conferences, including one in Finland, where he met Lenin for the first time; after a conference in Stockholm in April 1906, he wrote an anti-Menshevik creed that attracted the attention of the Bolshevik leader for the first time. Meanwhile, Stalin was also involved in banditry: as professional revolutionaries, the Bolsheviks were forced to turn to crime for financial support. In 1907, Stalin shifted his operations to the city of Baku, in Azerbaijan, and it was there, in March 1908, he was arrested for the second time and exiled for two years to the Siberian town of Solvychegodsk. He escaped within a year, but was re-arrested in March 1910 and returned to Siberia. This time, he served out his sentence, but remained politically active, writing letters to Lenin urging increased party organization within Russia. Released in June 1911, Stalin was ordered to remain outside of St. Petersburg, Moscow, and the Caucases (the southern region that included Georgia and Azerbaijan). He disregarded these orders, and made his way to St. Petersburg, where he was arrested yet again in December 1911, and shipped to the city of Vologda.
It was during this exile that the Bolshevik-Menshevik divide finally split the Social Democrats, as Lenin and his fellow Bolsheviks founded their own party in January 1912, at the Prague Conference. Given the power to appoint his own men to the new party's Central Committee, Lenin selected Stalin: the choice may have been a testament to the impression that the young "Koba" had made; but given how little Lenin knew about the yellow-eyed Georgian, it may also have been an indication of the lack of talent in the Bolshevik ranks.