Functionality and Usability, testing of digital library information services and products is essential for providing high quality services to users. This paper aims to detail a long-term, evolving effort to develop meaningful evaluations for assessing digital libraries. The evaluation protocols and approaches were designed iteratively over time through assessment efforts with other digital library initiatives and with multiple versions of the FEL. The research described in this paper relies on a combination of functionality and usability, evaluation strategies applied iteratively to assess libraries from the perspective of patron needs. These methodologies can provide detailed evaluations of the extent to which information and services are comprehensible for all users, the extent to which the features and functions necessary to provide library functions operate properly, and the extent to which the digital library meets the needs of a diverse population of users.
