Around 1900, French and Belgian Catholics adopted the projection lantern as a means of education and propaganda in reaction to successful initiatives of this kind by secularist organisations. In the north of France, near the Belgian border, the dioceses of Arras and Cambrai founded the Œuvre des Conférences et Catéchismes in Robaix, which provided a projection service distributing slides and lanterns. Belgian Catholics followed that example and cooperated in several ways with their French neighbours. This article describes the emergence and organisation of these projection services and their distribution practices. It also looks at the Catholics’ efforts to fight the Freemasons, who were considered the worst enemies of the Church. Finally, several slides from the Robert Vrielynck collection in Antwerp will be discussed, which bear witness to the propaganda strategies used by the Catholic Church.