This nine-step outline is designed for use by librarians and library trustees in obtaining a general estimate of their library's space needs and for initiating a more comprehensive, detailed facilities planning process. Identifiable spatial requirements to be assessed include space for collections, user seating, staff work, meetings, special use, and nonassignable space. These space needs are based on what must be housed in a library in order to serve its community adequately. Guidelines are then given for projecting future needs based on space requirements, and for translating the results of service assumptions into space needs. Examination of the library structure also reveals other areas of need/concern, such as improvement of energy efficiency; condition of the heating, ventilating, and air-conditioning system; accessibility to the handicapped; adaptability to future library technologies; and overall effectiveness of the work flow. Work space is provided throughout the text for calculations and notes, as well as sample floor plans and examples which illustrate how to make certain calculations. Appended materials include a list of representative types of special use space and a space needs worksheet. Twelve references are listed. (CGD)