Computers may have the potential to augment human cognitive processes in ways that could be beneficial for people with dementia. This possibility is being investigated by a multidisciplinary team. Previous work on improving the performance of augmentative communication systems for non-speaking people has shown the value of conversation modelling and prompting in this setting. The impairment of short-term memory with dementia causes serious difficulties in communication. A conversation support and prompting system is being developed based on an interactive multimedia reminiscence presentation. Reminiscence has been chosen as a basis for the conversations because long-term memories can remain relatively intact with dementia, even where short-term memory is ineffective. Initial trials of the system involving people with dementia and their carers have shown that such a system can maintain the interest and active participation of a person with dementia, and increase carers' enjoyment of the interaction. Further work will focus on directing the impact of multimedia towards increasing the quantity and quality of the communication taking place.