The SOG was founded in May 1975 when the Frente Obreiro (Workers Front) of the Galician People's Union decided to become a union.
[2] The SOG was part of the Galician National Popular Assembly (AN-PG).
The SOG defended "combative" unionism and rejected any kind o collaboration with the Patronal.
In April 1976 the organization held its first General Assembly.
However, it disappeared just a year later, in March 1977 to found, with other unions, the Intersindical Nacional Galega (ING).