Institutional repositories (IRs) are digital collections that capture and preserve the intellectual output of a single or multi-university community. Their aim is to provide access to scholarly material without the economic barriers that currently exist in scholarly publishing. If successful, IRs hold the promise of being very advantageous to researchers everywhere, especially those in the developing world. The IR concept is very new and has yet to be studied in any comprehensive way. This paper describes a study being conducted by the Canadian Association of Research Libraries to determine some success factors of institutional repositories. Through the CARL Institutional Repositories Pilot Project, several variables are being examined to determine whether they contribute to the input activity and use of the IRs being implemented at several Canadian research libraries. The project is in its initial stages, and has yet to show significant results. However, the paper presents a detailed description of the IR concept; identifies and explains the variables that are being studied; and discusses some of the challenges involved in the study.