In Leninist theory, a United front is a coalition of left-wing working class forces which put forward a common set of demands and share a common plan of action, but which do not subordinate themselves to the front, retaining their abilities for independent political action and continuing to hold different political programmes.

Leon Trotsky counterposed the idea of the united front against the Stalinist theory of a popular front, which could include bourgeois forces (e.g. liberals) and in which a minimum set of demands may be put forward, with the more militant demands of Communist groups being hidden or sublimated.