A library building consultant discusses ways in which public libraries can plan for the participation of their libraries in the National Information Infrastructure (NII). With participants ranging from schools to agencies of local government, large volumes of information will be passing through the NII network. Public libraries will be engaged in handling demands from users. Some users will make their demand for information exclusively from homes and offices, while others will continue to visit the library, possibly in increasing numbers. Public libraries will need far more power and telecommunications capability that ever before. The guide distinguishes between libraries less than 30,000 square feet in size and those of larger size, and discusses related concerns. Outreach services and more space requirements for staff functions are also addressed. For the larger library, employing a telecommunications consultant is recommended. This is especially important for the headquarters or central library which may be supporting several branches or affiliated libraries. Cautions are expressed against under-planning staff and public workspace. In conclusion, erring on the side of growth is proposed when planning space for both public and staff. (Contains four references.) (MAS)