This article focuses on the construction of dyslexia in higher education and explores the nature of negotiations between students, lecturers and academic institutions over diagnosis, support and assessment. Disabled students are now entitled, under the terms of the Disability Discrimination Act (DDA), to reasonable adjustments in assessment. However, there continue to be debates about the nature of dyslexia and the extent to which requests for reasonable adjustments threaten to compromise academic standards. The article begins with a brief overview of the provisions of the DDA and its implications for learning support and adjustments to assessment in higher education, before considering current debates in education over the nature of dyslexia and its implications for assessment in higher education. We then consider the incidence of dyslexia in higher education and the implications of the rapid growth in the number and proportion of disabled students in higher education for assessment practices. Subsequently, we present case studies of dyslexic students and discuss (a) the way in which dyslexia is understood by different actors and (b) institutional responses to claims for reasonable adjustment in teaching and assessment. (Contains 2 tables and 1 note.)