This paper reports a study of how context influences a content-based language teaching (CBLT) project in China, an approach which is fairly new in the country, in its implementation in three middle schools. It identifies three aspects of the context which have a crucial effect on classroom practice. These are the perceptions of the project and its objectives, as seen by the school principals, the parents and the teachers, who are stakeholders in the project; the curriculum content and resources; and the selection and development of the teachers. Following a discussion of these factors, the paper describes and discusses one CBLT lesson from the project. It shows how the opportunities and constraints imposed by these aspects of the context interact to bring about a mode of implementation that may be seen as unsatisfactory from a CBLT lesson perspective. It argues, however, that the implementation may be more appropriately seen in contrast to mainstream English lessons and, as such, is a legitimate and worthwhile response to the context within which the approach is implemented. (Contains 1 table.)