An automated library system usually consists of a number of functional modules, such as acquisitions, circulation, cataloging, serials, and an online public access catalog (OPAC). An "integrated" library system is an automated system in which all of the function modules share a common bibliographic database. There are several ways the integration of a system can be accomplished. The library can: (1) buy an integrated system from a single vendor; (2) purchase a variety of modules from different vendors and interconnect them; or (3) implement any number of purchased modules, then connect them to sources of information outside the library. Advantages of an integrated system include: duplication of effort in creating multiple copies of bibliographic records is eliminated; opportunities for errors are reduced when records are entered only once; and library staff and patrons can have access to all pertinent information at one location. Information is provided on the selection of an integrated system, implementation and management issues, and future trends in integrated library systems. A comparison is made between off-the-shelf and customized systems. (Contains seven references.) (MAS)