Solidarity and the Fourth International

Solidarity as a socialist organization understands that we need international collaboration in order to replace the domination and inequality of global capitalism. We seek fellow revolutionaries working to build social movements that can replace exploitation and oppression with a new society based on solidarity.

For several years prior to the 2025 World Congress of the Fourth International, Solidarity had been a sympathizing organization of the Fourth International (FI). At this year’s World Congress, Solidarity became the formal U.S. section. Founded on the eve of World War II by Leon Trotsky and revolutionary socialists, the FI and its sections today participate in struggles in the advanced capitalist countries as well as in post-colonial countries.

We see the Fourth International as a democratic and international body with a revolutionary presence in countries around the world. Networking with others who share our understanding that revolution can only be the product of a diverse working class and its allies, Solidarity participates in campaigns, discussions and debates in order to deepen our understanding. Through these experiences and exchanges, Solidarity and the network as a whole can strengthen our collective practice.

The Fourth International’s various resolutions, statements and articles are a record of this dialogue.

Fourth International websites and social media

Fourth International website

FI Facebook

FI Telegram

FI Twitter/X

International Viewpoint

Education institute (IIRE)

2025 World Congress pages

https://fourth.international/en/world-congresses/18th-world-congress-2025

Report

Fourth International Congress: taking the measure of the crisis of capitalism
Penelope Duggan and Antoine Larrache

Documents

Manifesto for an ecosocialist revolution – Break with capitalist growth

As the crises converge, the challenge of how the exploited and oppressed move forward

Our orientation and tasks in social movements

A resolution on party-building tasks for the Fourth International

Resolutions

Resolution on Ukraine: Fourth International World Congress

Palestine: An imperialist attack on the entire Middle East

No aggression against Syria

COP 30: catalysing a revival of the social and environmental struggle

Support and solidarity motions