With the advances in Quantum physics and meteorology, science has moved towards more uncertainty and unpredictability (Larsen-Freeman, 2002) . This has resulted in the emergence of Chaos/Complexity Science (Valle, 2000) , or Theory (Larsen-Freeman, 1997) , and Dynamic System Theory (De Bot, Lowie, & Verspoor, 2007) . As Larsen-Freeman (1997)  states the name of chaos/complexity science is paradoxical terminology in that the word science means order as well as complexity but in Ch/C this complexity is achieved through chaotic situation. In science we are searching for cause and effect connection while in Ch/C such a connection is not that much straightforward. Efforts have been invested to apply the concept into Second Language Acquisition (SLA) (Larsen-Freeman, 1997)  due to incommensurable issues in SLA Larsen-Freeman (1997) , especially, introduced the concept into SLA in detail, however, we think more works and speculations on the topic are required on all aspects which are related to SLA. To this end, this article is a critical review of the implication of Chaos/Complexity theory into SLA from three perspectives: the Nature of Language Complexity, SLA Incommensurable Theories, and the Complex Nature of Classroom.