Complex Dynamic Systems Theory (CDST) connects practice and research in ways that are abundantly illustrated in this excellent volume. The authors first person accounts make CDST accessible and show its relevance. The volume is sure to inspire practitioner-researchers to use the ecological approach afforded by CDST to investigate and make sense of the lived realities of their own classrooms. * Diane Larsen-Freeman, Professor Emerita, University of Michigan, USA * It is relatively easy to write complex things about complexity theory the real challenge is to follow the motto of the editors of this book, namely that complexity should be simple. This book goes a long way towards achieving this aim by gathering a well-chosen group of contributors whose deep interest in the real-life language classroom has created a common platform of down-to-earth complexity. The result is a thought-provoking and enlightening book. * Zoltán Dörnyei, University of Nottingham, UK * This volume opens up the world of applying a CDST perspective to research. With contributions that apply intriguing new designs and methods of data elicitation and analysis, readers will find that far from being terminological smoke and mirrors, CDST research can be made practical and useful. The result is a volume thoughtfully crafted in a way that enhances its accessibility and builds coherence in this still new but growing domain. * Phil Hiver, Florida State University, USA * The editors should definitely be applauded for compiling this impressive collection of papers and for their sincere efforts to make CDST more understandable to researchers and practitioners alike. Thinking back to the question I posed at the beginning of this review, there is no doubt that they have succeeded in making complexity simple for those who wish to research different aspects of the psychology of L2 learning and teaching through the lens of CDST. -- Mirosaw Pawlak, Adam Mickiewicz University, Poland * SSLLT 11 (1), 2021 * By focusing on situational factors, this volume does an excellent job at providing empirical designs and analyses of learner and teacher psychology both in traditional and subtle methods from the perspective of CDST. This volume is an inspirational reference for teachers, researchers, practitioners-as-researchers, and teachers-as-co-researchers with highlighting practice to dig deeply into L2 psychology and investigate more themes, particularly in teacher psychology. -- Siyu Duan, Changchun University of Finance and Economics, China * System, 2021 *