This article hopes to bring new insights to the debate about the effect of grammar knowledge on language use, especially writing. It raises the question of the need to look more closely at the following three questions: (1) What is the aim of grammar teaching?; (2) How capable are students of conceptualising about language and how is their metalinguistic activity shown in their language use?; and finally, (3) Which approach is most suitable for students to be able to develop their own knowledge, with emphasis on the role of interaction in the classroom? The article concludes with ten key points which provide a basic outline for progressing in grammar teaching research.