This landmark volume offers a collection of conceptual papers and empirical research studies that investigate the dynamics of language learning motivation from a complex dynamic systems perspective. The contributors include some of the most well-established scholars from three continents, all addressing the question of how we can understand motivation if we perceive it as continuously changing and evolving rather than as a fixed learner trait. The data-based studies also provide useful research models and templates for graduate students and scholars in the fields of applied linguistics and SLA who are interested in engaging with the intriguing area of examining language learning in a dynamic vein.