Abstract
According to social constructionism factuality, the establishment of accounts as corresponding to an objective external reality, is an interactional accomplishment ordinarily achieved in everyday conversations. In cases of disagreement regarding the interpretation and nature of events, however, not only the plausibility of the account, but also the rationality, integrity, and accountability of the participants is at stake. Delusions present extreme cases of such disagreement. This paper analyzes extracts from an interview with an individual diagnosed as delusional focusing on the factualization devices used in the negotiation of accounts. The question of whether the observation of conversational rules documented in the interview is sufficient to establish the plausibility of an account and the rationality of its teller leads to arguments around the necessity of shifting the focus from the grounded micro-analysis of talk to wider social and institutional processes.