As part of a growing body of conversation analytic research on epistemics in social interaction, this study explores various uses of the Japanese sentence-final particle "kke", which conveys the speaker's claim that she or he has some degree of uncertainty in recalling something from the past. The study aims to demonstrate how "mental" concepts like remembering and forgetting are grounded in, and bound to, communicative actions produced by interactants under the contingencies of everyday situations. To that end, the analysis shows how the act of claiming a particular mental state (i.e., uncertainty in recollection) is, in fact, motivated by such interactional concerns as acknowledging one's own responsibility for knowing something, invoking a particular social relationship with the recipient in bringing up a new conversational topic, and minimizing social disaffiliation when disagreeing with the previous speaker's assertion. (Contains 13 footnotes and 2 figures.)