In the early 1950s, Latin America represented as much a hope as a challenge for the Catholic Church. The continent sheltered the largest number of baptized people in the world, while Protestantism and communism were making rapid advances, accelerating the desertion of churches. Faced with this phenomenon, the Holy Seat created a network of training institutions and dispatched priests to Latin America. The Belgian institution was the College pour l'Amerique latine (COPAL) of Louvain, founded in 1953. In this context, the author analyzes the evolution of the Catholic relationship with Protestantism through papal speeches as well as through fieldwork, via COPAL's bulletin and three books on Latin America published between 1959 and 1969 whose authors were connected with the Louvain institution.