Factions of the Russian Social Democratic Labour Party

• Bolsheviks formed in 1903 from the major split in the RSDLP which also produced the Mensheviks. This faction followed Vladimir Lenin, and organised a separate party, the Russian Social Democratic Workers Party, aka Russian Social Democratic Labour Party, in 1912. After the October Revolution, it became the Communist Party of the Soviet Union.
• Borba, an expatriate group based in Paris.
• Jewish Labour Bund had an autonomous statute inside the RDSLP between the first congress in Minsk in March 1898 and the second congress in Brussels and London in August 1903, and again from the Fourth Congress in Stockholm in April 1906.
• Liquidators were a faction of the Mensheviks who left in 1905, maintaining that with the availability of legal participation in political life, the underground revolutionary party must be liquidated.
• Mensheviks formed from the 1903 split with the Bolsheviks, under the leadership of Julius Martov. With the formal severing of ties in 1912, the Mensheviks used the name Russian Social Democratic Party, or sometimes without the qualifier. At the outbreak of World War I, the majority supporting the war maintained control of the RSDLP under Fyodor Dan and others, while those opposed to the war left as the Menshevik Internationalists under Martov.
• Menshevik Internationalists were the faction who opposed involvement of Russian socialists in the war effort, who split from the Mensheviks in 1914 under that faction's founder, Martov. It eventually merged with Mezhraiontsy, which later merged with the Bolsheviks.
• Mezhraiontsy formed in 1913 to attempt bridging the divide between the Bolsheviks and the Mensheviks, but eventually merged in 1917 with the Bolsheviks.
• Otzovists were a group of radical Bolsheviks who demanded to cease all participation of the RSDLP in legal state establishments, in particular, to recall the RSDLP representatives from the State Duma, hence the name. Among the prominent Otzovists were Alexander Bogdanov, Mikhail Pokrovsky, Anatoly Lunacharsky, and Andrei Bubnov. The debates among Bolsheviks whether to boycott the new constituency of the Russian parliament known as the Third Duma started after the defeat of the revolution in mid-1907 and the adoption of a new, highly restrictive election law. This faction subsequently organised itself in the Vpered group.
• Ultimatists were a radical faction of Bolsheviks which demanded that an ultimatum must be sent to Bolshevik deputies of Duma demanding them to be uncompromisingly radical. While Vladimir Lenin sided with them twice, he eventually denounced them, dubbing them "liquidators inside out". Ultimatists controlled the St. Petersburg Bolshevik organization until September 1909.
• Yedinstvo were associates and followers of Georgi Plekhanov.
• Yuzhny Rabochy, opposed to the Iskra programme of building a centralised party.