Solidarity is a unity of purpose or togetherness - see solidarity (sociology). The term has been adopted as a name by a variety of entities:
- Solidarity, the Polish trade union originally led by Lech Wałęsa
- Solidarity (US), the United States political organization formed by the fusion of the International Socialists, Socialist Unity, and Workers' Power
- Solidarity Party, an American political party founded by Adlai Stevenson III in the state of Illinois.
- Solidarity (newspaper), the newspaper published by the Alliance for Workers Liberty in the UK.
- Solidarity (UK), was a revolutionary syndicalist organisation in the United Kingdom during the 1960s and 1970s.
- Solidarity – The Union for British Workers, a UK trade union
- La Solidaridad, a group of Filipino propagandists and the name of their newspaper that were active in the end of the 19th century.
- Solidarity (Australia), a Sydney-based socialist revolutionary outfit founded in 2003.
- Solidarity was a political movement in British Columbia during the spring to fall of 1983, adopting the name used by the contemporaneous Polish movement. Its two main organizations were the broadly based Solidarity Coalition, which had its roots in Vancouver's Peace Movement of the early 1980s, and the organized labour-based Operation Solidarity
- Solidarity Forever - a famous anthem of the leftist and trade-union movements.
- Solidarity - a monthly magazine published by the United Auto Workers.
- Solidarity a South African trade union with a large white, Afrikaner membership base.
- Labour Solidarity - a movement founded by Roy Hattersley in 1981 to resist the Left in the British Labour Party and halt defections on the Right to the Social Democrat Party: it lasted two years and played a role in preserving a centrist egalitarian component to the Labour Party and weakening the Social Democrat Party challenge