The People's Socialist Front or Popular Socialist Front (Portuguese: Frente Socialista Popular, FSP) was a socialist political party in Portugal, founded in 1974. It was a breakaway group from the Socialist Party.^[1]

The group was founded in December 1974 by Manuel Serra,^[2] a Marxist who had previously attempted to become leader of the Socialist Party. He had been imprisoned for several years during the authoritarian Estado Novo regime.^[3] Under his leadership, the FSP took place in violent demonstrations, including riots in Setúbal.^[4]

In the 1975 Constituent Assembly election, the FSP received less than 5% of the vote and won zero seats.^[5]

The FSP ran candidates in the 1976 legislative election,^[1] and participated in the 1976 local election in coalition with the Portuguese Communist Party and the Portuguese Democratic Movement inside the Electoral Front United People.^{[citation needed]}

On 7 July 2004, after several years of inactivity, the party was declared extinct by the Portuguese Constitutional Court.^{[citation needed]}