As libraries automate their collections and mount online public access catalogs (OPACs), they face special challenges in educating patrons to use these electronic systems effectively and efficiently. Because users are less familiar with the concept and arrangement of an OPAC than with a card catalog, less successful searches commonly occur. Uninitiated users tend to rely on the comfortable author, title, and subject approaches, and miss portions of available information. Furthermore, users often become frustrated by high recall/low precision retrieval and their inability to negotiate a successful search query. Since the OPAC is not merely an automated card catalog, librarians must establish an instructional program to help users conceptually understand and use the sophisticated searching features the OPAC offers. As libraries add external databases to their local holdings and offer remote access to the OPAC, they become information centers without walls, and it becomes essential that users have a clear understanding of how to retrieve desired information in a timely manner. (26 references) (Author/SD)