- an international association formed in 1889 in Paris, uniting socialistic groups or parties of various countries and holding international congresses from time to time: in 1923 it joined with the Vienna International to form the Labor and Socialist International.
- an international association of socialist parties and trade unions that began in Paris in 1889 and collapsed during World War I. The right-wing elements reassembled at Berne in 1919
- another name for the Labour and Socialist International
