After a short overview of classical neuropsychological knowledge about the disorders of written language, the authors review the data of cognitive psychology in this field. They first consider the general principles of cognitive analysis and then describe the specific syndromes of phonological and lexical routes impairment both in reading and writing. The possible correlations between these syndromes and other higher brain function impairments or anatomical localization are briefly considered. Finally an analysis of the impairments to peripheral writing processes, i.e. graphemic buffer and allographic conversion system syndromes, is given. In conclusion the contribution of cognitive psychology to daily neuropsychological practice is discussed.