At the time of the split in the Russian Social Democratic Labour Party into the Mensheviks under Julius Martov and the Bolsheviks under Vladimir Lenin in 1903 she did not side with either faction. However, she came to dislike aspects of Bolshevism and opted to join the Mensheviks.
In 1915 Kollontai joined the Bolsheviks and returned to Russia, after a period of exile for her earlier political activities. After the Bolshevik takeover in October, 1917 she became Commissar for Social Welfare. She was the most prominent woman in the Soviet administration and was best known for founding the Zhenodtel or "Women's Department" in 1919. This organization worked to improve the conditions of womens' lives in the Soviet Union, fighting illiteracy and educating women about the new marriage, education, and working laws put in place by the Revolution. It was eventually closed by Stalin in 1930.
In government Kollontai became an increasing internal critic of the Communist Party and joined with her friend, Alexander Shlyapnikov to form a left-wing faction of the party that became known as the Workers' Opposition. However, Lenin managed to dissolve the Workers' Opposition, after which Kollantai became more or less totally politically sidelined.
When Joseph Stalin gained power he sent Kollontai abroad as a diplomat. In 1923, she became the world's first woman ambassador, serving in Norway, and later in Mexico and Sweden; she was also a member of the Soviet delegation to the League of Nations. Kollontai died on March 9, 1952.
She is an unusual figure in the history of the Soviet Union as she was a major public critic of the Communist Party that was neither purged or executed by the Stalin regime.