This statement of principles embodies a general approach to the nature and objectives of preservation and conservation work relating to library materials. It does not aim to provide a comprehensive list of detailed methods and practices, but is intended to establish a responsible attitude toward preservation and conservation by librarians. The document is divided into five major sections. The introduction includes discussions of aims and definitions, objectives, functions of libraries, library policies, problem assessment, selectivity, links with other libraries and library functions, implications of preservation policies, training, and cooperation. The second section, Preservation, considers factors related to storage and accommodation, temperature and humidity, light, air pollution, dust and cleanliness, storage materials and equipment, buildings, and standards employed. The section on the Security of the Collections includes discussions of fire, water, war and natural disaster, theft, and disaster preparedness. A section on Use of the Collections includes discussions of document protection and storage, library materials in transit, readers and reader facilities, copying, reprography policy, exhibitions, limiting use, and substitutes. The final section, Factors Affecting Deterioration, includes discussions of biological factors; micro-organisms; insects and other pests; chemical factors; and damage to paper, leather and parchment, photographic film, and nitrate film. (THC)