Although it is crucial for libraries to meet required online accessibility standards (e.g., Web Content Accessibility Guidelines 2.0), compliance with these technical standards does not guarantee optimal or equitable experiences for all library users who interact with online spaces or materials. Recent literature on accessibility testing has acknowledged the value of including people with disabilities in testing and designing digital objects and spaces. This thinking aligns with the library-based user experience (UX) principle that talking directly to users about their experiences using library services and resources is the most effective way to understand and thereby improve the overall library experience. In 2020, the UX Group at Western Libraries undertook a pilot accessibility testing initiative to plan, design, and deliver participatory accessibility testing with campus community members who had self-identified as living with a range of disabilities. Three accessibility tests were designed to assess five distinct digital objects, and 14 testing sessions were completed with eight participants. A semi-structured and participatory testing method allowed participants to freely interact with the testing objects, provide detailed feedback regarding their experiences using the objects, and recommend improvements to elements they found less accessible. This article includes an overview of considerations and challenges of the initiative as well as lessons learned in the process of securing funding, recruiting participants, designing the tests, and conducting testing. We reflect on the value of participatory accessibility testing and make recommendations for conducting similar projects at other libraries.