Principles of universal design – in education generally and in assessment specifically – inform Chapter 10. There are few, if any, classrooms consisting solely of ‘regular’ children. Rather, the diversity of the human condition in terms of ability, background, capacity and emotion is present to greater or lesser degrees in most schools and classes. Accommodating the needs of such diverse learners is expected in modern education systems which are themselves not immune to enormous social and cultural influences and shifts in population. Schools and teachers respond to diversity in complex ways. Many large-scale assessment programmes have evolved to reflect the needs of diverse learners through a range of accommodations and modifications as part of the development, administration and scoring of tests. Teachers, similarly, can amend practice through a variety of differentiated adjustments for both formative and summative approaches. This can elicit more accurate accounts of student learning and, therefore, ensure that the benefits of assessment are not benefits attainable only by some students. The chapter identifies a range of assessment-related challenges for students with disabilities, gifted students, those with a language different to that used in school and those exhibiting other atypical learning profiles, offering possible approaches and solutions.