thumb|Crowds gathered in front of the main building of Warsaw University of Technology for the Unification Congress of the Polish Workers' Party and Polish Socialist Party (15 to 21 December 1948) On December 14, 1948 The 2nd Congress of the PPR and the 28th Congress of the PPS were held simultaneously, at which the decision was made to unite both parties. The Polish United Workers' Party was established at the unification congress of the Communist Polish Workers' Party and the Polish Socialist Party during meetings held at the main building of the Warsaw University of Technology from 15 to 21 December 1948. The unification was possible because the PPS had effectively been taken over by pro-Communist fellow travelers, and the activists who opposed unification had been forced out of the party. Similarly, the members of the PPR who were accused of "rightist–nationalist deviation" () were expelled. Thus, the merger was actually an absorption of the PPS by the PPR, resulting in what was a renamed and enlarged PPR for all intents and purposes.
thumb|Crowds gathered in front of the main building of Warsaw University of Technology for the Unification Congress of the Polish Workers' Party and Polish Socialist Party (15 to 21 December 1948) On December 14, 1948 The 2nd Congress of the PPR and the 28th Congress of the PPS were held simultaneously, at which the decision was made to unite both parties. The Polish United Workers' Party was established at the unification congress of the Communist Polish Workers' Party and the Polish Socialist Party during meetings held at the main building of the Warsaw University of Technology from 15 to 21 December 1948. The unification was possible because the PPS had effectively been taken over by pro-Communist fellow travelers, and the activists who opposed unification had been forced out of the party. Similarly, the members of the PPR who were accused of "rightist–nationalist deviation" () were expelled Thus, the merger was actually an absorption of the PPS by the PPR, resulting in what was a renamed and enlarged PPR for all intents and purposes.