The Spanish Regional Federation of the International Workingmen's Association, known by its Spanish abbreviation FRE-AIT, was the Spanish chapter of the socialist working class organization commonly known today as the First International. The FRE-AIT was active between 1870 and 1881 and was influential not only in the labour movement of Spain, but also in the emerging global anarchist school of thought.

The International Workingmen's Association (IWA), often called the First International (1864–1876), was an international organisation which aimed at uniting a variety of different left-wing socialist, social democratic, communist and anarchist groups and trade unions 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.