Clara Zetkin proposed the idea of an International Women’s Day at the 1910 International Socialist Women’s Conference.
Zetkin was a German socialist politician, activist, and editor who made women’s political rights central to her work. At the conference in Copenhagen, she and fellow German delegate Käte Duncker proposed an annual day focused on women’s rights, including the campaign for women’s suffrage. The delegates represented 17 countries, and the proposal was accepted without a fixed date.
The first major observances followed in 1911, when more than a million people participated in events in Austria, Denmark, Germany, and Switzerland. The date was later standardized as 8 March, a development strongly connected to women’s demonstrations during the Russian Revolution of 1917.
Zetkin is sometimes confused with Alexandra Kollontai, another prominent socialist women’s-rights campaigner. Kollontai helped popularize the observance in revolutionary Russia, but Zetkin is the canonical answer for proposing the annual international day in 1910.