SPT was led by its general secretary Boonsanong Punyodyana.

[1][2] SPT won 15 out of 269 seats in the 1975 parliamentary elections.

[3] That election, which was the first free polls after many years of dictatorship, also saw other left-wing parties like the New Force Party (12 seats) and Socialist Front (10 seats) represented in Parliament.

After the Thammasat University massacre and military coup on 6 October 1976, many SPT cadres went into exile or joined the Communist Party of Thailand's guerrillas in the border areas with Laos in northern Thailand and Isan (northeastern Thailand).

Thus the party was dissolved at the order of the military junta’s National Administrative Reform Council leader Sangad Chaloryu on 6 October 1976.