This paper discusses the design of flexible and intelligent library buildings. The first section addresses how flexibility, as one of the requirements of a library building, that has high priority in the planning process. Intelligent libraries are considered in the second section, and functionality is stressed. The third section examines conditions for buildings facing the next century, including the shortcomings of fixed standards and guidelines, new developments in computer and network technology, and changing user needs. Programming issues are discussed in the next section. The fifth section looks at planning conditions related to the preparation for a new city library in The Hague (Netherlands), including: main functions; teamwork; the architect's brief, which sets out the general philosophy and requirements of the library; and cost control. The role of the Programme Management Group during the planning process of the library in The Hague is described in the sixth section, followed by two sections that summarize the use of a "spacebook" and datasheets. The ninth section lists concerns that librarians will need to address in library planning. Examples of library buildings in the Netherlands that were designed to meet future needs are presented in the last section. Several related conclusions are offered. (MES)