TEP was founded in 1975, and sought to fill the political void created by the banning of the Workers' Party of Turkey (TİP) in 1971.

[5][3][6][7][2] Other prominent founding members of TEP included Vecdi Özgüner, Şaban Ormanlar, Sevki Aksit, Mustafa Özçelik, Halil Oyman, Erol Yüce, Sefer Yılmaz and Faik Kalkavan.

[8][9] TEP distinguished itself from the other contemporary legal socialist parties by upholding the National Democratic Revolution [tr] ('MDD', per its Turkish acronym) line.

[3][6] The party argued that Turkey would have to undergo a democratic transformation, abolishing remnants of feudalism, before being ready for transition to socialism.

[12] In August 1975, TSİP appealed for a united front of socialist and leftist forces ahead of the October 12, 1975 Senate election.

[3] In the end the meetings did not result in a united front, as the participating parties could only agree to the formation of a Consultative Socialist Bureau.

[2] On June 7, 1976 a trial of 33 leading TEP members began at the Istanbul State Security Court [tr], based on an indictment dated April 21, 1976.

[7][6] The verdict found the TEP guilty of "attempting to create a sense of minority in the mind of a certain group of citizens [that] is contrary to the concept of the unity of the State with its territory and nation".

[16] On May 24, 1980 there was another Grey Wolves attack on the party – in which TEP executive committee member Vecdi Özgüner was wounded at his residence and his wife Sevinç was shot to death.

[2] In 1982 TEP took part in the founding of the Unified Resistance Front against Fascism (FKBDC), in which the Kurdistan Workers' Party (PKK) and Dev-Yol were the dominant factions.