The SLMP supported the Provincial Council Act and ran against the United National Party (UNP) in 1988.
The party lost 117 leading members during the revolution of 1988–89, including Vijaya Kumaranatunga, Pohoddaramulle Pemaloka Thero, T. B. Wijesuriya, and Deva Bandara Senarathne.
The People's Alliance won the 1994 presidential election, and Chandrika Kumaranatunga became the president of Sri Lanka.
In the legislative elections on 2 April 2004, the United People's Freedom Alliance won 45.6% of the popular vote and 105 out of 225 seats.
Dr Navarathne died on 1 May 2013, and his son, Asanka Nawaratne, the deputy general secretary of the party, succeeded him.