Given in narrative, tables, and diagrams are the average space requirements for assigned areas, technical equipment, and communication areas which constitute the net area of a research library. The assigned area of a research library consists of storage space for collections, space for readers, space for information and circulation services, staff areas, and utility areas. Communication areas consists of staircases, landings, passages, etc. serving the general traffic of the building. Layout suggestions and methods of calculating the space requirements of open stacks, closed stacks, card catalogs and periodical stacks are given. From a description of an average university, a model of the necessary library system is calculated. (Author/PF)