Notions of authenticity have helped to structure the values and frames of reference of linguistics, sociolinguistics and pragmatics without, until lately, being widely discussed. Despite this recent attention, authenticity remains problematic in various ways. It is notoriously hard to define, paradoxical, often vacuous, and yet, it clearly still matters. While, from a postmodern vantage point, it may be argued that authenticity is discursively constructed rather than given, not a property of things in themselves but of how human agents choose to imagine and value them, this does not reflect the hold that the term continues to exert. One has to bear in mind its continuing moral, emotive and ideological force. In the intense debates over identity and belonging in the modern world, speakers are quite ready to claim languages and cultures they do not know as authentically ‘theirs’. It is likely to be more useful for linguists to consider how speakers use the notion of authenticity, the ideological ends it is made to serve, and the nature of the authenticating practices in which they engage. It is also more realistic to acknowledge that our own terms, assumptions and research activities are not value-free; the problem is not that we too have ideological purposes, but that we may still present them as somehow independently given and authorized.