Intellectual disability is usually thought of as a form of internal, individual affliction, little different from diabetes, paralysis or chronic illness. This study, the first book-length application of discursive psychology to intellectual disability, shows that what we usually understand as being an individual problem is actually an interactional, or social, product. Through a range of case studies, which draw upon ethnomethodological and conversation analytic scholarship, the book shows how persons categorized as 'intellectually disabled' are produced, as such, in and through their moment-by-moment interaction with care staff and other professionals. Mark Rapley extends and reformulates current work in disability studies and offers a reconceptualisation of intellectual disability as both a professionally ascribed diagnostic category and an accomplished - and contested - social identity. Importantly, the book is grounded in data drawn from naturally-occurring, rather than professionally orchestrated, social interaction.