When Arbetarpartiet Kommunisterna (Workers Party - the Communists) broke out of VPK in 1977, they founded a youth league with the name SKU.
Later a large section of the Gävleborg district of KU affiliated itself to SKU.
SKU published a magazine called Gryningen (The Dawn).
In the late 1980s SKU started to become associated with an oppositional stream within APK.
On May Day 1990 in Stockholm SKU marched together with KU and Ungsocialisterna (youth of Socialist Party) under the banner of "Youth against Capitalism and Stalinism".