The aim of this paper is to consider how theoretical linguistics can contribute to providing learners with metalinguistic knowledge and developing their grammatical awareness in the school curriculum, with special reference to the relation between generative grammar and English as a foreign language (EFL) in Japan. Back in 1970s, generative grammar and EFL were much more intimate than they are now, but along with the theoretical development of generative grammar in 1980s, English teachers came to give it the cold shoulder. Their divorce was inevitable because teachers in those days attempted to introduce technical details of generative grammar directly into the classroom. In light of the lessons in the past, I argue that it is important to distinguish the knowledge employed by learners to organize their interlanguage grammar and the knowledge necessary for teachers to arrange their teaching materials, and that the metalinguistic knowledge obtained from generative grammar primarily fall into the latter category. Specific areas of contribution from generative grammar to EFL include, among others, the awareness of constituent structure, the distinction between arguments and adjuncts, and the interaction between lexical information and grammatical rules.