The 'Père Castor' Archives were methodically built by Paul Faucher, founder of the Père Castor, until his death in 1967. It includes documents for its beginnings as a bookseller at Flammarion (1921) but mostly documents for the design, manufacture and distribution of the collection "Les albums du Père Castor" (1931-1967). This corpus, made up of very diverse forms and media (notes, correspondence, illustrations, prints, recordings, photographs, drawings ...), includes educational reflection materials that have gradually led to the collaborative creation, collaborative but highly structured and thoughtful, from what is better known under the name of "Les albums du Père Castor". These children’s books which Russian , German, Polish, Czech, Dutch, Swedish, Belgian and French designers have collaborted, are now considered to be classics of the children literature, and have been translated into twenty languages. These books and educational games designed by the Atelier du Père Castor, made efficient and accessible to the greatest number, the theoretical knowledge of teachers of the movement of the New Education.