International Working Union of Socialist Parties

International Working Union of Socialist Parties
Internationale Arbeitsgemeinschaft Sozialistischer Parteien
AbbreviationIWUSP
IASP
SecretaryFritz Adler
FoundedFebruary 27, 1921 (1921-02-27)
DissolvedMay 21, 1923 (1923-05-21)
Preceded bySecond International
Succeeded byLabour and Socialist International
IdeologyCentrist Marxism
Democratic socialism
Anti-Bolshevism
Political positionLeft-wing
Colors  Red

The International Working Union of Socialist Parties (IWUSP; also known as the 2½ International or the Vienna International; German: Internationale Arbeitsgemeinschaft Sozialistischer Parteien, IASP) was a political international for the co-operation of socialist parties.