The Democratic Left Party (Turkish: Demokratik Sol Parti, DSP) is aTurkish political party. The social democratic oriented party was founded in November of 1985 by Rahşan Ecevit, spouse of Bülent Ecevit as he was banned from political life after the military coup of 1980.

In 1986 Bulent Ecevit addressed the DSP convention in Ankara, declaring his support for the party. The address landed him in court for allegedly violating the political bans. The DSP was unable, however, to achieve a substantial showing in the 1986 by-elections even though Ecevit, despite his ban, continued to campaign at the party's rallies as a "guest speaker".

The political ban on Ecevit was lifted following a referendum in 1987. Later that year, Rahşan Ecevit handed over the rule of the party to her spouse. But the party failed to pass the 10% national threshold needed for a political party to have a seat in Parliament in the 1987 elections, urging the Ecevit's to step down from their positions in the party.

In 1988, Necdet Karababa was elected as the new party leader. However, already the next year, Ecevit was reelected as party chairman in a party convention. Two years later in 1991, the DSP received 10.75% of the votes in the elections allowing the party to have 7 seats in the Parliament. This also meant the return of Ecevit to the Parliament after 11 years.

It was a minority party until it won 76 parliamentary seats in the December 1995 elections. Again in 1995, the party started to suffer from inner conflicts after years of serenity. The inner conflicts in the party ended with the dismissal of Erdal Kesebir and three other DSP members.

In 1997, the DSP became a member of a three-way coalition government led by Mesut Yilmaz who at the time was the leader of the Motherland Party. Ecevit became the deputy prime minister.

In 1998, the 55th government of Turkey was toppled by a censure motion. Ecevit received the mandate to form a new government. He founded a minority government in 1999 to carry the country to general elections.

Boosted by the capture of the leader of the terrorist PKK organization, Abdullah Öcalan, during his prime ministry, DSP won 22,19% of the votes in the elections of April in 1999 and took 136 of the 550 seats in the Turkish Parliament becoming a major party. It's leader Bülent Ecevit became then for the fifth time Prime Minister of Turkey.

Tension, economic crisis and conflicts both in the government and inside the DSP reached a peak in 2001. The party convention held in the same year was the scene of serious controversies. Some members resigned and some were dismissed. In 2002, Ecevit was hospitalized twice. All these were the beginning of a process that ended with the resignation of the government and melting of the party. His confidents and a number of DSP members resigned from the party and founded the New Turkey Party.

Following the November 3 elections in 2002, the DSP failed to pass the national threshold getting only 1.2% of the votes and remained outside Parliament. Shortly after the elections defeat, Bülent Ecevit announced that he would step down as party leader and leave active politics. In 2004, Ecevit repeated this statement and named Zeki Sezer, deputy chairman since 2001, as his heir. At the 6th extraordinary party convention on July 25, 2004, Zeki Sezer was elected as the new leader of the party.

The DSP approves of Turkish adhesion to the European Union, although it criticized the content of the Customs Union.