The International Workingmen's Association (IWA, 1864–1876), often called the First International, was an international organization which aimed at uniting a variety of different left-wing socialist, communist and anarchist political groups and trade union organizations that were based on the working class and class struggle. It was founded in 1864 in a workmen's meeting held in St Martin's Hall, London. Its first congress was held in 1866 in Geneva.