To determine the most popular entries on library ready reference web sites and the role of visibility in the selection of resources.
Ready reference web sites of 100 American libraries were examined, for a census of the most frequently selected online resources. The dates of news, library and online media coverage were considered for specific tools, to explain their prominence.
Early publicity for web tools was found to be an important element in their relative popularity as choices for library web sites.
The date on which a given web resource became well known among librarians can only be estimated from media reports, not proved. Additional study could establish the frequency with which libraries modify their ready reference web sites and investigate why other resources of comparable quality have not become as popular.
The paper shows that early visibility plays a role in librarians' selection of web resources that is rarely mentioned in discussions of selection criteria.
