The best aggregations of Web resources combine authoritative informati
on, effective retrieval mechanisms, and dependability of access. The w
orst can be incomplete, inaccurate, and difficult to use. Libraries ca
n expand their Web holdings and maintain high-quality information serv
ices by selecting aggregations based on objective standards of content
, coherence, and functionality. These three criteria can also be used
to plan the most effective presentation of aggregated resources in the
library's catalog or Web pages.