The University of Pennsylvania Library and the Taylor-Schechter Genizah Research Unit at Cambridge University Library in England have embarked on a project to digitize their joint holdings of manuscript fragments from the Cairo Genizah. One goal of this collaboration is to develop and implement an online catalog and image database for the University of Pennsylvania's collection of Genizah fragments, which will provide the foundation for a global electronic repository and catalog of the entire Cairo Genizah. The project staffs have developed preliminary guidelines for standardized descriptive metadata. The authors discuss the issues and difficulties specific to cataloging these fragments, how an online catalog can facilitate this ambitious task, and why MARC tagging was adopted for this purpose.