International Workingmen's Association

The International Workingmen's Association (IWA), often called the First International, was an international organisation which existed from 1864 to 1876 and aimed at uniting a variety of different left-wing socialist, communist, and anarchist political groups and trade union organisations that were based on the working class and class struggle. It was founded on 28 September 1864 at a workers' meeting in St Martin's Hall, London, and its first congress was held in 1866 in Geneva. The IWA's membership peaked in 1871–72 at around 150,000, with a wider periphery of sympathisers.

In 1872, it split into two factions over the growing conflict between its statist and anti-statist wings. The statist wing, led by Karl Marx, advocated for the participation of the working class in the state electoral process. The anti-statist wing, led by Mikhail Bakunin, opposed any participation in the state electoral process and advocated for its abolition. The conflict led to the expulsion of Bakunin and the anarchists from the International at the Hague Congress. In response, the anti-statist wing formed their own International at the St. Imier Congress. The statist wing of the International, led by Marx, moved its General Council to New York City, where it ultimately disbanded in 1876. The anti-statist wing of the International continued until 1877, with some sections continuing into the early 1880s.

The IWA is considered a foundational event in the history of socialism. The Second International was formed in 1889 as a successor. The International Working People's Association, also known as the Black International, was formed in 1881 as a successor to the anti-statist wing of the First International.