People with dementia living in residential care often face the dual disadvantage of increasing difficulty with communication and reduced opportunities for conversation. Social interaction is central to wellbeing of residents with dementia, so it is important that care staff have the skills to engage in conversation with them. We studied conversations in 20 care staff-resident dyads, to examine conversation structure and content, patterns of engagement within conversations, including the topics around which engagement occurred, and communication behaviours by care staff that appeared to facilitate (or impede) participation by residents. The transcripts were analysed using Discursis, a computational information visualisation tool that allows interactive visual inspection, in context, of the contributions by each speaker, the turn-taking dynamics, and the content recurring within and between speakers. We present case examples (a) where care staff did most of the talking, initiated topics and were responsible for most recurrence of content; (b) where talk was more evenly shared between partners, with some topics initiated and/or elaborated by participants with dementia; and (c) where participants with dementia talked most, with care staff supporting the conversation. We identified accommodative strategies used by care staff, such as reflecting back the other person's responses to sustain engagement. We also noted care staff behaviours that impeded communication, such as not listening attentively and not allowing sufficient time for responses. The results from this study highlight aspects of social communication within the aged care context and suggest ways in which rewarding interactions between staff and residents with dementia might be encouraged.