It was founded in 1984 with the union of the Galician Socialist Party (PSG) and Galician Left, led by Camilo Nogueira Román.

In 1993 the PSG-EG formed with nationalist centre-left sectors a new Galician Unity coalition.

In the general and autonomic elections of 1993 the party concurred with the United Left (EU) coalition, forming the Galician Unity-United Left (UG-EU) coalition.

After the defeat in the elections, some members of the party converged with EU forming the Galician Left-United Left and the others joined the Galician Nationalist Bloc as Galician Unity.

The party had 2 mayors: Narón (1985-1993) and Porqueira (1984-1987).