1. Introduction In this chapter, we discuss how MAP Grammar can lead learners to use English outside the confines of the language classroom by introducing an English for Specific Purposes (ESP) genre-based approach. MAP Grammar helps learners understand how and where to use particular grammatical points based on meaning and can increase learners’ intelligible output with fewer difficulties. We argue that for learners to use English beyond the classroom, we should first recognize that the basis of MAP Grammar is closely related to the ideational metafunction of Systemic Functional Grammar (SFG) proposed by Halliday and other like-minded linguists. Ideational metafunction, one of the three categories of language use, mainly concerns our understanding and construal of the world and the content of messages. MAP Grammar is a resource to help learners express their ideas and make meaning through creating and understanding sentences, thus supporting ideational metafunction yet leaving some room for specific contexts in which to achieve meaningful communication. This social aspect of language is integral to any communication, which is conceptualized together with two other metafunctions: interpersonal and textual metafunctions. A language is both semantic and functional, and SFG considers it a “system of meanings” (Bloor & Bloor, 2013, p. 2). When we use language to make meanings, we always do so in specific situations, and the grammar, vocabulary, tone (for speaking), and style of