Snowling and Coltheart and Jackson provide an excellent overview of the contemporary cognitive and linguistic approach to the description and definition of dyslexia. Both contributors consider dyslexia to be a disorder of written language. Snowling focuses on the origins of the difficulty in a central ‘phonological deficit’. Coltheart and Jackson emphasise the internal modular structure of the reading and spelling systems, suggesting that different components may be impaired in different individuals, resulting in distinctive (phonological and surface) patterns of dyslexia. Both conclude that future research might focus on implications for effective programmes of treatment.