This research offers a triangulation of historical sources to look into day-to-day life at private religious schools for boys in the post-Civil War period in Spain (1939-1945). The article will compare information from other studies on these schools with information provided by a new source: the testimonies of former pupils. The text offers a comparative analysis between the recollections of former pupils from certain schools and the reports that teacher training students wrote on the same schools on their placements there during the time the interviewees were pupils. The work aims to provide information on a little-known topic: educational practice at private religious schools. In turn, it reflects on the features and value of the historical sources used.