The political slogan "Workers of the world, unite!", one of the most famous rallying cries of socialism, comes from Karl Marx and Friedrich Engels's Communist Manifesto. The actual translation is more normally given as "Working men," or "Proletarians of all countries, unite!"

The slogan was the USSR State motto in 15 languages.

It is sometimes extended to "Workers of the world unite, you have nothing to lose but your chains", mixing the three last sentences of the Communist Manifesto.

It is widely known and oft-quoted, and also frequently adapted, for example in The Smiths' song "Shoplifters of the World Unite" or the bumper sticker "Dyslexics of the world, untie!"