Ensuring that educational tests are accessible to students with disabilities is a core aspect of fairness in assessment, regardless of the exact uses of the testing. Disability accommodations, as well as universally available accessibility features, can facilitate that access, but determining which supports to offer should be guided by sound empirical research and defensible theoretical frameworks. Here the guest editors introduce a special issue of Assessment for Effective Intervention on this topic of accessibility in assessment. We discuss the importance of the topic, we provide an overview of each article in the issue, and we offer reflections on the present and future of research on this topic.