The article reports on a case study that investigates (1) the extent to which Chinese English teachers' views on teaching communicative English in the FL classroom setting are compatible with their teaching behaviours, and (2) the possible causes of the observed incompatibilities between their views and practice. Based on Richards and Rodgers' (1986) description of communicative language teaching (CLT) principles, a questionnaire was first developed which elicited the views of three Chinese English teachers on CLT principles. Observations were then made of their teaching behaviours in oral English classes for a week. Finally, each of them took part in an interview in which they responded to questions about the observed discrepancies between their views on CLT principles and their practice in teaching. The major findings are: (1) Although the participants all agreed with CLT principles, they spent most of the time on text-based exercises, which provided few opportunities for genuine communication. (2) The participants' responses revealed that what prevented them from fully applying CLT principles were mainly their ignorance of the students' communicative needs, their deep-rooted perception of teaching as one-way transmission of knowledge, and the washback effect of existing ways of student assessment. The relationships of these constraints are further discussed.