The Spanish Red Cross (Cruz Roja Española, or CRE) provided medical aid to wounded soldiers during the war and retained close links with the international medical community. An apolitical organization, the Spanish Red Cross was then, as it is today, one of several national Red Cross societies forming the International Red Cross.

The Foyer du Français Antifasciste served as a vehicle for French citizens to affirm their support for the Spanish Popular Front. During this time, the government of France maintained an ambivalent position on the war, having succumbed to international pressures that led to the eventual closure of the border with Spain. The choice of figures to adorn the stamps above suggests the political solidarity of the Forum with the Republican cause.

International Red Aid (Socorro Rojo Internacional, or SRI) provided wartime support to the civilian population, especially children. Founded in 1922, SRI was tied to the Communist International. Unlike the impartial CRE, SRI maintained a close working relationship with the Spanish Communist Party.

Similar in many respects to the groups listed above, International Antifascist Solidarity (Solidaridad Internacional Antifascista, or SIA) offered aid to Republican Spain. The group was created and maintained by anarchist sympathizers in France and elsewhere.