The Left Youth (Vasemmistonuoret in Finnish, Vänsterunga in Swedish) is a political youth organization in Finland. It is considered the youth wing of the Left Alliance, but it is not officially affiliated with the party - members of the Left Youth are not automatically members of the Left Alliance. The organization was founded in 1944. Until 1998, it was known as the Finnish Democratic Youth League (SDNL, Suomen demokraattinen nuorisoliitto) and until 1990 it served as the youth organization of the now-defunct Finnish People's Democratic League (SKDL). SDNL was a founding member of World Federation of Democratic Youth, but its main international frame used to be the European Network of Democratic Young Left until its dissolution.

Chairpersons