The Systemic-functional Linguistic model (SFL) (Halliday 2004), with its main focus on the explanation of language use in context, has been widely applied in educational settings around the world, both from research and pedagogical perspectives. However, the applications of SFL to foreign language acquisition at lower educational levels are still very scarce. This paper provides an overview of SFL inspired foreign language classroom research at pre-primary, primary and secondary levels, with the application of two SFL models: Halliday’s (1975) functional model of child language development and genre and register theory. The chapter shows the advantages of SFL for the understanding of foreign language students’ use of lexico-grammatical features to convey different meanings and functions, as well as to participate in the registers and genres of academic disciplines. It also illustrates the role of SFL in SLA research and the interest of combining SFL and other compatible approaches in the study of SLA in educational contexts.