In view of ongoing debates about the future of task-based language teaching (TBLT) in contexts of English as a foreign language (EFL), we present a detailed case study of teacher beliefs and practices regarding TBLT conducted in a secondary school in mainland China with a long history of communicative and task-based teaching approaches. We used a mixed-methods approach to gather a broad range of triangulated data, combining individual interviews, material analysis and observations coded using a novel task-focused version of the scheme ‘Communicative Orientation of Language Teaching’ (COLT). Quantitative and qualitative findings revealed positive beliefs about TBLT principles in general, reflecting strong institutional support for communicative teaching. However, there was marked variability between beliefs and practices in using tasks, especially with beginner-level learners. Most teachers demonstrated an intrinsic lack of confidence in using tasks as more than a communicative ‘add-on’ to standard form-focused teaching. We argue that this demonstrates a need for building teacher autonomy, in implementing TBLT, even in supportive settings, to support successful authentic contextualizing TBLT principles in different EFL contexts.