Young Left was founded in 1903 as Socialdemokratiska Ungdomsförbundet (SDUF, Social Democratic Youth League). However, the youth league has clearly attached itself to the left-wing within the Social Democratic Party. At the outbreak of the First World War, the tensions within the party aggravated. In May 1917, the youth league together with the left-wing faction within the party took the initiative to form a new party, Sverges socialdemokratiska vänsterparti (Social Democratic Left Party of Sweden). SDUF became the youth wing of the new party. SSV joined the Communist International in 1919, and was renamed to Sveriges kommunistiska parti (Communist Party of Sweden). Following that, SDUF was renamed to Sveriges Kommunistiska Ungdomförbund (Young Communist League of Sweden), and became the Swedish section of the Communist Youth International.