As part of the ArchivesSpace Public User Interface implementation at Yale University Library, a Usability and Accessibility Workgroup was formed and tasked with assessing the usability and accessibility of the new ArchivesSpace PUI. Set to replace the current Yale Finding Aid Database (YFAD), the PUI presents archival description in a very different way than current static online finding aids. To set priorities and make decisions about visuals, data display, site structure, settings, and other enhancements, our team conducted qualitative facilitated usability tests with users from our target audience. Working with representatives from five user groups – undergraduate students, graduate students, faculty, library staff, and outside researchers - we conducted 16 usability tests between February 1, 2018 and February 16, 2018 in a test instance of the PUI. We also tested the site for compatibility with screen readers and for WCAG 2.0 compliance. Results of the tests were compiled in a report with recommendations that address confusions, road blocks, and frustrations faced by users. As is often the case, usability and accessibility issues overlapped, providing a stronger argument for some key changes. We would like to present our process for usability testing along with a few findings from our report.