During this time there were two parties using the term "PSL": Polskie Stronnictwo Ludowe Piast and Polskie Stronnictwo Ludowe Wyzwolenie. During World War II, PSL took part in forming the Polish government in exile. After the war the leader of PSL, Stanislaw Mikolajczyk, returned to Soviet occupied Poland, hoping to recreate the party structures and create anti-communist opposition. To prevent this, the Soviet-controlled communist government formed a puppet PSL-Piast and, after rigging an important referendum, forced the real PSL to unite with it, forming United People's Party — a satellite of the Communist Party. Mikolajczyk was soon forced to flee the country into political exile..
Around the time of the fall of communism several PSL's were recreated, including: Polskie Stronnictwo Ludowe - Porozumienie Ludowe, Polskie Stronnictwo Ludowe - Odrodzenie, and Polskie Stronnictwo Ludowe (Wilanów faction). In 1989 they merged into one and took part in forming the first postwar noncommunist government in Poland with the Solidarity grouping, and in 1990 changed its name to PSL.
It originally remained on the left wing of politics in Poland in the 1990s, entering into coalitions with the postcommunist Democratic Left Alliance. However, in the 2001 parliamentary elections PSL received 9% of votes and formed a coalition with Democratic Left Alliance, an alliance which later broke drown. Since then PSL has moved towards more centrist policies. The party ran in the 2004 European Parliament election as part of the European People's Party (EPP) and received 6% of the vote, giving it 4 of 54 Polish seats in the European Parliament. In the 2005 general election the party received 7% of votes, giving it 25 seats in the Sejm and 2 in the Senate. In the 2007 parliamentary elections the party placed fourth, with 8.93% of the vote and 31 out of 460 seats, and entered into a governing coalition with the victor, the liberal-conservative Civic Platform (Platforma Obywatelska).