Party of Democratic Socialism, a political party in West Bengal in India. PDS was founded in February 2001 by expelled CPI(M) leader Saifuddin Chaudhury. PDS is in opposition to the Left Front government in West Bengal, and they have aligned themselves with the Indian National Congress.

Initially there was talks of a tie-up with the All India Trinamool Congress or that PDS would be a constituent of an anti-CPI(M) mahajot (broad front), but the link between Trinamool and the Hindu rightist BJP hindered such a development.

PDS has formed relations with other pro-Congress leftist outfits, such as Communist Marxist Party in Kerala and the United Communist Party of India .

Ahead of the West Bengal state assembly elections in 2001 PDS had launched their own front. PDS put up 98 candidates, whom together got 219 082 votes (0,6% of the votes in the state). None of their candidates got elected.

Ahead of the Lok Sabha elections in 2004 PDS had joined hands with Congress, and put up two candidates supported by Congress.

The flag of PDS is a red flag with a red star in a white circle.

The president of PDS is Saifuddin Chaudhury, general secretary Samir Putatunda (formerly the CPI(M) South 24 Paraganas district secretary) and the treasurer is Subir Chaudhury.

The women's organization of PDS is called Paschim Banga Nari Sanghati Samiti (West Bengal Women's United Association). The president of PBNSS is Kishwar Jahan.

PDS publishes Amader Katha (Our Voice).