This article uses the situated cognition and functional pragmatics paradigms to explain how a broad and holistic understanding of the (healthcare) set-up in which dialogue interpreting assignments take place enables interpreters to develop an awareness of the purpose-orientation of medical professionals’ (inter)action plan. This understanding forms part of an inferential mental backdrop that allows interpreters to go from bottom-up drifting to gaining top-down control over their task. On the basis of a corpus of 19 interpreter-mediated doctor-patient encounters, the article suggests that it is acting upon an integral background of understanding as inferential basis (rather than role) that empowers dialogue interpreters to perform successfully.