Public participation broadcasting has recently become the focus of attention in media studies, as well as from the social interactional perspectives of discourse and conversation analysis, and it has been argued in particular that the talk show genre has given new and enhanced status to the 'authentic' voice of lay members of the public. What remains largely unexplored is how lay participants discursively construct authentic positions for their own knowledgeable participation in such discourse. Expert speakers in public participation broadcasts are typically attributed names, rank, institutional affiliation and status, which legitimizes their position, and in so doing provides their warrant to talk about whatever issue they have been brought in to discuss. Lay participants typically do not have this status attributed to them, but need to establish their own position from which to talk. In this article I examine the public identities that lay speakers build for themselves in these broadcasts, and show how they routinely draw on a range of discursive resources to construct situated, local identities which provide a warrant for what they have to say.