The National Center on Educational Outcomes (NCEO) supports the participation of students with disabilities and English learners in educational assessments by conducting research and offering guidance on accessibility. Its work spans all types of assessments—formative, classroom-based, diagnostic, interim, and summative—ensuring that all students have opportunities to demonstrate their knowledge and skills. NCEO collaborates with states, districts, and national organizations to promote policies and practices that improve assessment systems for all learners.