The inaugural Women’s Day event, known as “National Woman’s Day,” was reported to have occurred on February 28, 1909, in New York City.

It was organized by the Socialist Party of America^[12] at the suggestion of activist Theresa Malkiel.^[13] There have been claims that the day was commemorating a protest by women garment workers in New York on March 8, 1857, but researchers have described this as a myth intended to detach International Women’s Day from its socialist origin.^[14][15][16]

In August 1910, an International Socialist Women’s Conference was organized ahead of the general meeting of the Socialist Second International in Copenhagen, Denmark.^[17] Inspired in part by the American socialists, German delegates Clara Zetkin, Käte Duncker, Paula Thiede, and others proposed the establishment of an annual “Women’s Day”, although no date was specified.^[8][14][18] The 100 delegates, representing 17 countries, agreed with the idea as a strategy to promote equal rights, including women’s suffrage.^[19]

The following year, on March 19, 1911, the first International Women’s Day was marked by over a million people in Austria-Hungary, Denmark, Germany, and Switzerland.^[12] In Austria-Hungary alone, there were 300 demonstrations,^[14] with women parading on the Ringstrasse in Vienna, carrying banners honoring the martyrs of the Paris Commune.^[14] Across Europe, women demanded the right to vote and to hold public office, and protested against employment sex discrimination.^[4]

IWD initially had no set date, though it was generally celebrated in late February or early March. Americans continued to observe “National Women’s Day” on the last Sunday in February, while Russia observed International Women’s Day for the first time in 1913, on the last Saturday in February (albeit based on the Julian calendar, as in the Gregorian calendar, the date was March 8).^[20] In 1914, International Women’s Day was held on March 8 for the first time in Germany, possibly because that date was a Sunday.^[20] As elsewhere, Germany’s observance was dedicated to women’s right to vote, which German women did not win until 1918.^[20][21] Concurrently, there was a march in London in support of women’s suffrage, during which Sylvia Pankhurst was arrested in front of Charing Cross station on her way to speak in Trafalgar Square.^[22]