There is a wide array of accessibility features (e.g., universal features, designated supports, accommodations) which enable students who need them to better access assessments. Historically, however, there has been wide variation in the language used to describe these supports. For example, the accessibility policies of different states use different terms for the same support. Similarly, different test vendors use different terms to describe the same support, which can lead to confusion when the policies of different tests within a single state refer to the same accessibility feature by different names (NCEO, n.d.; Shyyan et al., 2016; Warren et al., 2016). To address this issue, the National Center on Educational Outcomes (NCEO) collaborated with the Common Education Data Standards (CEDS) initiative to bring together stakeholders representing state education agencies (SEAs), test vendors, and assessment consortia to develop common accessibility feature terms and definitions. The purpose of this activity was to establish standardized accessibility terminology and data elements within CEDS that enable clear communication between education stakeholders and ensure equitable assessment opportunities for all students, particularly students with disabilities, English learners, and English learners with disabilities. Once the stakeholders agreed on the definitions, the proposed definitions were submitted to the CEDS initiative for possible inclusion in their data elements. CEDS was developed by the U.S. Department of Education's National Center for Education Statistics (NCES) to establish a standardized vocabulary and data models for education data elements.