For secondary English teachers concerned with the theoretical and practical problems of the traditional approaches to teaching grammar, this paper proposes that a realistic solution can be found in current linguistic investigation. This solution lies not in the product of linguistic inquiry, but in the process of inquiry itself. The paper first summarizes three basic linguistic insights as background for a method of linguistic inquiry that has proved effective in showing the complex and systematic nature of language, yet does not require any prior knowledge of either grammatical theory or of the principles of the method itself. The major portion of the paper illustrates this method with a question-and-answer sequence on the use of the tag question in English. (CC)