It has often been proposed that computer programs simulating written conversation could be effective in language teaching and remediation. This paper presents a theoretical rationale for this approach, and reports empirical studies of its potential. Although the studies were concerned mainly with language-impaired children, their findings should have some relevance for the wider field of computer assisted language learning in general.Several microcomputer programs were developed to hold written dialogue with children about screen graphics. Studies of the software in use over several months by two different groups of language-impaired children produced evidence to suggest that experiences associated with the software led to improved skills in the language covered by the programs. The studies also produced new ideas about the kinds of language leamLng activities which might be promoted by this kind of software.The paper concludes with suggestions about how these ideas might form the basis of future intelligent tutoring systems able to prescribe a variety of language learning activities, over a range of language materials.