Solidarity's victory in the 1989 Polish legislative election occurs, the first election since the Communist Polish United Workers' Party abandoned its monopoly of power. It sparks off the Revolutions of 1989 in Eastern Europe.

Solidarity, full name Independent Self-Governing Trade Union "Solidarity", is a Polish trade union founded in August 1980 at the Lenin Shipyard in Gdańsk, Poland. Subsequently, it was the first independent trade union in a Warsaw Pact country to be recognised by the state.

Parliamentary elections were held in Poland on 4 June 1989 to elect members of the Sejm and the recreated Senate, with a second round on 18 June. They were the first elections in the country since the communist government abandoned its monopoly of power in April 1989 and the first elections in the Eastern Bloc that resulted in the communist government losing power.

The Polish United Workers' Party, commonly abbreviated to PZPR, was the communist party which ruled the Polish People's Republic as a one-party state from 1948 to 1989. The PZPR had led two other legally permitted subordinate minor parties together as the Front of National Unity and later Patriotic Movement for National Rebirth. Ideologically, it was based on the theories of Marxism-Leninism, with a strong emphasis on left-wing nationalism. Later, in 1988-1989 some factions of the party adopted milder democratic socialism, which was seen as the impact of the perestroika in the neighbouring Soviet Union. The Polish United Workers' Party had total control over public institutions in the country as well as the Polish People's Army, the UB and SB security agencies, the Citizens' Militia (MO) police force and the media.

The revolutions of 1989, also known as the Fall of Communism, were a wave of liberal democracy movements that resulted in the collapse of most Marxist–Leninist governments in the Eastern Bloc and other parts of the world. This wave is sometimes referred to as the Autumn of Nations, a play on the term Spring of Nations sometimes used to describe the revolutions of 1848. The revolutions of 1989 were a key factor in the dissolution of the Soviet Union—one of the two superpowers—and abandonment of communist regimes in many parts of the world, some of which were violently overthrown. These events drastically altered the world's balance of power, marking the end of the Cold War and beginning of the post-Cold War era.