We report a qualitative study of accounts of interpreted consultations in UK primary care. The study sought to explore how three Habermasian tensions between (a) system and lifeworld, (b) communicative and strategic action, and (c) interpersonal and macropolitical spheres played out in the triadic consultation between clinician, interpreter and patient. In a total of 69 individual interviews and two focus groups, we collected narratives from service users (through interpreters or bilingual researchers), interpreters and doctors and other staff in general practice. We recorded, transcribed and analysed these, taking the story as the main unit of analysis. Our data suggest that the preconditions for communicative action are rarely met in the interpreted consultation. The interpreter's presence makes a dyadic interaction into a triad, adding considerable complexity to the social situation and generating operational and technical challenges. Lack of trust, intense pressure of time, mismatch of agendas (biomedical versus lifeworld), firm expectations of a specific outcome (e.g. referral, prescription) and profound power imbalances all promote strategic action (i.e. speech that seeks consciously or unconsciously to manipulate an outcome) rather than communicative action (i.e. sincere efforts to achieve understanding, and reach consensus) by all parties. In consultations interpreted by family members (an option traditionally seen as 'second best' by policy makers), the social situation is very different. Family members are generally trusted, share the lifeworld agenda, and shift the power balance in the patient's favour. The interpreter occupies multiple social roles, including translator, interpersonal mediator, system mediator, educator, advocate, and link worker. The essence of professionalism in interpreting is shifting judiciously between these potentially conflicting roles. We discuss the implications of our findings for communication with limited English speakers in healthcare consultations and for realizing contemporary policy goals such as concordance, shared decision-making, empowerment, and choice.