A case of agraphia was studied in the framework of the information-processing approach and in relation to comparable studies on alexia. Three dissociations are of interest in this patient's picture: (a) in language production: impairment of writing without impairment of speech; (b) in writing: impairment of spelling without impairment of phoneme-grapheme conversion; (c) in visible language: impairment of writing without equivalent impairment of reading. The implications of these dissociations for any model of linguistic processes are discussed.