English language teachers may be interested in learning how the application of Complex Dynamic System Theory can impact English language teaching and learning. This theory emphasizes the  interplay of three levels - micro, meso, and macro - in shaping language teaching and learning. The micro level delves into action and interaction from language teachers and learners in multi-lingual contexts, while the meso level considers sociocultural institutions and communities. The macro level functions as the overarching language ideology.  A detailed review, based on a  corpus of 198 studies published from 2008 to 2022 on second language learning and teaching, identified three research themes: the language itself, L2 learners and learning, and L2 teachers and teaching.