The Socialist Party (Italian: Partito Socialista, PS) is a moderate social-democratic[2] political party in San Marino.

During the Sammarinese election of 2012 the party joined the unsuccessful centrist coalition of the Agreement for the Country, even if the party itself obtained quite good results gaining 7 seats.

The alliance formed the opposition to the Adesso.sm alliance led by the Democratic Socialist Left, which one the second round runoff election on 4 December 2016.

The party has been characterised as "friendly" by the former Foreign Minister of South Ossetia.

[4] In April 2024 the party launched an alliance with the PSD and Libera San Marino for the 2024 general election,[5][6] within which the PS and Libera share an electoral list.