This Council on Library and Information Resources (CLIR) report summarizes and analyzes more than 200 recent research publications that focus on the use of electronic library resources (digital libraries and digital resources) and were published between 1995 and 2003. Eight major ongoing studies (each with multiple publications) are identified as Tier 1 studies and are analyzed in detail, while about 100 smaller-scale studies are classified as Tier 2 studies and are examined together. The goal of this report is to provide information that librarians can use to make important decisions about collections, services, and product design. (Contains 3 figures.) [Assistance in writing this document was provided by Brenda Hitchcock and Ashley Pillow.]