[4] It was founded in 1952 when the Socialist Party, led by Jayaprakash Narayan, Rambriksh Benipuri, Acharya Narendra Deva and Basawon Singh (Sinha), merged with the Kisan Mazdoor Praja Party led by J.

B. Kripalani (former president of the Indian National Congress and a close associate of Jawaharlal Nehru).

The PSP led the cabinet under Pattom A. Thanu Pillai as chief minister of State of Travancore-Cochin from March 1954 to February 1955.

[5] The PSP again came to power in the new state of Kerala under Pattom A. Thanu Pillai from February 1960 to September 1962.

[6] At the party's first general election in 1957, the PSP won 10.41% of the total votes and 19 seats in the Lok Sabha.