Task-based teaching is an area which has emerged from the upsurge of interest in cognitive approaches to language learning and teaching of the mid-1980s. Being a current vogue in communicative language teaching, task-based language learning contains dangers if implemented without care. In particular, it is likely to create pressure for immediate communication rather than interlanguage change and growth. In this process, it may persuade learners to use lexical modes of communication excessively and prematurely, and to fossilize some way short of native-like second language competence. This paper takes a processing-pedagogic viewpoint to review what task-based instruction is, to identify its goals, and to warn EFL/ESL teachers about the potential pitfalls of task-based language teaching. (Contains 1 figure.)