Krashen’s (1981, 1982) acquisition-learning hypothesis (ALH) is a well known concept that has been taught in applied linguistics for over 30 years. It has also been adapted into many other fields of study such as education (Gee, 1989), composition (Tricomi, 1986) and neuroscience (Kuhl, 2004). While it may be said that the basic concept of the ALH represents a foundational aspect of communicative approaches to teaching English and the emergence of socio-cultural theory (Lantolf, 2006), it is nevertheless hotly contested by other applied linguists for the inability of the ALH to make an empirical distinction between the seemingly amorphous line between acquisition and learning. This paper examines the theoretical implications of the ALH within applied linguistics as well as extrapolating on the theoretical implications of Gee’s (1989) use of the ALH for his theories of literacy. In doing so, the analysis in this paper not only traces theoretical moves from the ALH to theories of literacy, situated learning, intertextuality, and representation, all of which are gaining expanded attention in applied linguistic literature and practice. In addition, the analysis shows that the dichotomy of the ALH is representative of an epistemological divide across the social sciences, including applied linguistics.