It is one of the member parties that composed the United Nationalist Democratic Organization (UNIDO) that supported the candidacy of Corazon Aquino and Salvador Laurel in the 1986 Snap Elections against President Ferdinand Marcos.

In the year 2000, the PDSP mobilized with civil society organizations and groups in support of the impeachment, which led to eventual removal of former President Joseph Estrada from office.

The PDSP then helped much to consolidate the newly restored democracy, especially through education and mobilization among the small farmers and fisherfolk, workers, urban poor, women, youth, Bangsamoro, and the indigenous peoples of Luzon, Visayas and Mindanao.

[2] Starting in 1996, the PDSP actively participated in the interfaith dialogues held between Christian and Muslim groups in the Philippines.

These series of events led to the formation of the Bishops Ulama Conference[3] (BUC) with Romeo Intengan, S.J.