Abstract
Grammar is significant in learning other language skills, such as speaking and writing. Theories of teaching grammar in a foreign language are vital as they allow EFL teachers to build a frame for language learners. Grammar instruction is a bridge that links learners with other skills and if their grammar competence is vulnerable, the whole language production will be weak too. This study seeks to understand and review language theories that underlie daily grammar teaching. Many of EFL/ESL teachers teach grammar without a solid understanding of the language theories that inform their actual teaching practices and methodologies. This paper sheds light on the linguistics theories underlying grammar teaching methodologies in most English as foreign language classes and textbooks. It is significant for English teachers to have a basic knowledge of language acquisition theories as it directly influences their ability to provide appropriate content area instructions.