Solidarity (Polish: „Solidarność”, pronounced [sɔliˈdarnɔɕt͡ɕ] ^ⓘ), a Polish non-governmental trade union, was founded on August 14, 1980, at the Lenin Shipyards (now Gdańsk Shipyards) by Lech Wałęsa and others. In the early 1980s, it became the first independent labor union in an Eastern Bloc country. Solidarity gave rise to a broad, non-violent, anti-Communist social movement that, at its height, claimed some 9.4 million members. It is considered to have contributed greatly to the Revolutions of 1989.

The People's Republic of Poland attempted to destroy the union by instituting martial law on December 13 1981, followed by several years of political repression but in the end was forced into negotiation. The Roundtable Talks (February 6 to April 5 1989) between the Communist government and the Solidarity-led opposition resulted in semi-free elections of 1989. By the end of August 1989, a Solidarity-led coalition government had been formed, and Wałęsa was elected president in December 1990. This was soon followed by the dismantling of the Communist governmental system and by Poland's transformation into a modern democratic state. Solidarity's early survival represented a break in the hard-line stance of the Communist Polish United Workers' Party (PZPR), and was an unprecedented event; not only for the People's Republic of Poland — a satellite of the Soviet Union ruled by a one-party Communist state — but for the whole of the Eastern Bloc. Solidarity's example led to the spread of anti-Communist ideas and movements throughout the Eastern Bloc, weakening Communist governments. This process later culminated in the Revolutions of 1989.

In the 1990s, Solidarity's influence on politics of Poland waned. A political arm of the Solidarity movement, Solidarity Electoral Action (AWS), was founded in 1996 and would win the 1997 Polish parliamentary election, only to lose the subsequent 2001 Polish parliamentary election. Thereafter, Solidarity had little influence as a political party, though it became the largest trade union in Poland.

In the 1970s and 1980s, the initial success of Solidarity in particular, and of dissident movements in general, was fed by a deepening crisis within Soviet-influenced societies. There was declining morale and worsening economic conditions (a shortage economy). After a brief boom period, from 1975 the policies of the Polish government, led by Party First Secretary Edward Gierek, precipitated a slide into increasing depression, as foreign debt mounted. In June 1976, the first workers' strikes took place, involving violent incidents at factories in Płock, Radom and Ursus. When these incidents were quelled by the government, the worker's movement received support from intellectual dissidents, many of them associated with the Committee for Defense of the Workers (Polish: Komitet Obrony Robotników, abbreviated KOR), formed in 1976. The following year, KOR was renamed the Committee for Social Self-Defence (KSS-KOR).

On October 16, 1978, the Bishop of Kraków, Karol Wojtyła, was elected Pope John Paul II. A year later, during his first pilgrimage to Poland, his masses were attended by hundreds of thousands of his countrymen. The Pope called for the respecting of national and religious traditions and advocated for freedom and human rights, while denouncing violence. To many Poles, he represented a spiritual and moral force that could be set against brute material forces, he was a bellwether of change, and became an important symbol—and supporter—of changes to come.

Strikes did not occur merely due to problems that had emerged shortly before the labor unrest, but due to governmental and economic difficulties spanning more than a decade. In July 1980, Edward Gierek's government, facing economic crisis, decided to raise prices while slowing the growth of wages. At once there ensued a wave of strikes and factory occupations, with the biggest strikes taking place in the area of Lublin. The first strike started on July 8, 1980 in the State Aviation Works in Świdnik. Although the strike movement had no coordinating center, the workers had developed an information network to spread news of their struggle. A "dissident" group, the Workers' Defence Committee (KOR), which had originally been set up in 1976 to organize aid for victimized workers, attracted small groups of working-class militants in major industrial centers. At the Lenin Shipyard in Gdańsk, the firing of Anna Walentynowicz, a popular crane operator and activist, galvanized the outraged workers into action.

On August 14, the shipyard workers began their strike, organized by the Free Trade Unions of the Coast (Wolne Związki Zawodowe Wybrzeża). The workers were led by electrician Lech Wałęsa, a former shipyard worker who had been dismissed in 1976, and who arrived at the shipyard late in the morning of August 14. The strike committee demanded the rehiring of Walentynowicz and Wałęsa, as well as the according of respect to workers' rights and other social concerns. In addition, they called for the raising of a monument to the shipyard workers who had been killed in 1970 and for the legalization of independent trade unions. The workers may have timed the strike to coincide with the nearby Intervision Song Contest, which many international journalists attended. On August 16, an agreement had been reached under which the government agreed to raise wages at the Lenin shipyard and reinstate several sacked workers, which the union agreed to accept in exchange for ending the occupation of the Lenin shipyard while the issue of free trade unions was left unresolved. When the agreement was announced, there was a grass-roots revolt led by several of the striking women workers who demanded the right to free trade unions being guaranteed as a number of strikes in the 1970s had been ended with similar agreements only for the state to renege later on.

The Polish government enforced censorship, and official media said little about the "sporadic labor disturbances in Gdańsk"; as a further precaution, all phone connections between the coast and the rest of Poland were soon cut. Nonetheless, the government failed to contain the information: a spreading wave of samizdats (Polish: bibuła), including Robotnik (The Worker), and grapevine gossip, along with Radio Free Europe broadcasts that penetrated the Iron Curtain, ensured that the ideas of the emerging Solidarity movement quickly spread. The strike attracted immense media attention in the West and Western journalists swarmed into Poland to cover the crisis.