Information Interdependence is an empty concept unless the real user is a dominant element. The individual user of information must be sensitized to the existence of information interdependencies and to the critical need to foster much more of it, if libraries are to survive economically and provide exemplary information service. Three approaches to library collection building attempt to deal with the obvious inability to buy it all: (1) to predict needs through measures of use; (2) to develop resource sharing mechanisms with other institutions in a region; and (3) to develop the bibliographic apparatus to permit locating material regardless of where it resides. Five developing national activities are leading toward the latter ability: (1) national bibliographic control; (2) a national serials data base; (3) a national lending library for journals; (4) machine-readable cataloging for book form materials; and (5) the Ohio College Library Center. To aid in organizing a regional network, a computer simulation has been developed by six libraries in Western Pennsylvania to model acquisitions decisions and processes, technical processing, circulation, and public services for participating libraries. Analysis of circulation records of the University of Pittsburgh conducted as part of an effort to predict collection needs indicates that only half of the collection circulates at all. Further analysis will investigate the relationship between circulation and in-house usage. (Author/PF)