The Belgian section of the Entraide internationale socialiste, the Entraide Socialiste, is founded by the POB during the Spanish Civil War as part of a vast movement of solidarity with the Spanish republican fighters and their families. It became Solidarité Socialiste in 1978.

As a consequence of the Congo's independence, two organisations are created within the Entraide Socialiste: the Entraide aux boursiers d’Afrique, a reception and accommodation service, today SETM-Solidarité Etudiants Tiers Monde and the Fonds National de Coopération au Développement (FNCD), a development cooperation organisation responsible for development micro-projects, mainly in Africa.

The FNCD incorporates the Belgian Committee to fight hunger, recently created following the call launched by the FAO to developed nations to combat hunger and poverty in the world, and more commonly known by the name SOS Faim.

The FNCD is one of the organisations that create the CNCD.

Following the coup d'état by General Augusto Pinochet who overthrew Salvador Allende in Chile, the Entraide Socialiste supports Chilean exiles fleeing the dictatorship.

Entraide Socialiste takes the name of Solidarité Socialiste.

The French- and Dutch-speaking wings of Solidarité Socialiste separate: one becomes FOS - Socialistische Solidariteit and the other Solidarité Socialiste-FCD (Fonds de Coopération au Développement).

Solidarité Socialiste applies a new working logic which starts by strengthening and networking southern civil society organisations from around ten countries; the FADOC (Fonds d’appui à la dynamisation des organisations communautaires de base) focused on defending democracy, human rights and social change.

Solidarité Socialiste changes its name and is now called Solsoc.