Interpreter-Mediated Healthcare Communication engages conceptually and empirically with the ongoing debate concerning the ‘influence’ occasioned by the participation of an interpreter – whether professionally trained or as a lay family member – in healthcare delivery. Healthcare delivery, especially in the primary care sector, is increasingly becoming multicultural and multilingual in character. This global reality manifests itself as a communicative challenge in interpreter-mediated healthcare consultations, involving professional as well as family members in the role of interpreters. In the context of this book (previously published as a special issue of the journal Communication & Medicine), interpreter-mediated healthcare consultations are seen simultaneously as multilingual and multiparty interactions, as well as being dyadic and triadic communication. The introductory editorial sets the scene by foregrounding the core notion of ‘communicative vulnerability’ of all participants –