Socialist Workers Front (Marxist–Leninist)

Socialist Workers Front (Marxist–Leninist) (Frente Obrero Socialista (marxista-leninista)) was a communist party in Panama. FOS(ml) was founded in 1973, following a split in the People's Party of Panama. FOS(ml) originated in the pro-Chinese 'Proletarian Wing' of PPP. FOS(ml) made its first public appearance on May Day 1973.

FOS(ml) was mainly active in the students movement. It also organized the Asociación de Amistad con la República Popular China. FOS(ml) published Bandera Roja (Red Flag) 1974–1980.

The general secretary of FOS(ml) was Enrique Castillero.

In 1980, FOS(ml) was dissolved following internal strife. One section would live on as the Communist Party (Marxist-Leninist) of Panama.