It is a universal responsibility of librarians to perform their work in the best economic interests of society. This concern for economy applies as well to the design and construction of their library buildings as it does to the management and administration of their collections and services. This paper addressees three specific aspects of that responsibility when new buildings are being planned: (1) economy in the design and construction of library buildings; (2) the economy with which patrons can use new library buildings; and (3) the economy with which new library buildings can be adapted when necessary to meet the changing nature of information handling and services.