One of the most influential recent attempts to develop a teaching approach linked to findings from SLA has come from American applied linguist, Krashen. In the 1970s and 1980s, Krashen argued strongly for rejection of the audiolingual method on the grounds that second languages developed much like first - through implicit acquisition. He drew inspiration from Chomsky's idea of an innate Language Acquisition Device (the early term for Universal Grammar - see section 2.2.3.2), but also from research on how speech to acquiring children is modified (see 2.2.3.3) and on stages of development in interlanguage (see section 2.1.4). He developed a set of five hypotheses known as either the Monitor Model or the Input Model on which he and Tracy Terrell then based their Natural Approach to second language teaching (Krashen and Terrell, 1983). This approach stresses that language classrooms need to provide lots of target language input which learners can - and are motivated to - understand; teachers then need to let learners engage their natural ability to develop knowledge of the target language implicitly by ensuring a stress-free environment. Formal learning, such as the presentation of grammar rules and error correction, is rejected as, at best, irrelevant and at worst, a hindrance to second language proficiency. All teachers should focus on is making language meaningful to learners at the different levels: the grammar will arguably take care of itself. Thus, there is no need for any grammatical or structural syllabus.

Insofar as the Natural Approach argues that a second language is best developed through meaningful use of that language, and not through the accumulation of grammatical structures, Krashen's views can be seen to support the broader Communicative Approach to language teaching. Despite its limitations, the Natural Approach is one of the few teaching approaches which draws directly on SLA research, and as such, we shall now examine it in some depth.