Condensing and correlating information from about 40 sources (1955-1979), this leaflet discusses the destructive effects on paper of acids introduced in the manufacture, and of theenvironmental conditions: temperature, relative humidity, light and atmospheric pollutionunder which paper is kept in libraries and archives. It emphasizes the value of air conditioning, air filtering and the minimization of exposure to light, and advises a year of monitoring before designing control installations. -- AATA