The International Union of Socialist Youth (IUSY) (founded in 1907), is a global political youth organisation, representing socialist and organised labour youth organisations. IUSY's work centers around supporting its member organizations, publishing bulletins, and organizing international annual youth gatherings.
Founded in 1907 as the youth wing of the Second International under the name Socialist Youth International, IUSY now represents 134 member organisations in over 80 countries. IUSY is an international youth NGO with UN ECOSOC consultative status, which it gained in 1993.