This edited volume brings together both established and emerging researcher voices from around the world to illustrate how complexity perspectives might contribute to new ways of researching and understanding the psychology of language learners and teachers in situated educational contexts. Chapter authors discuss their own perspectives on researching within a complexity paradigm, exemplified by concrete and original examples from their research histories. Moreover, chapters explore research approaches to a variety of learner and teacher psychological foci of interest in SLA. Examples include: anxiety, classroom group dynamics and group-level motivation, cognition and metacognition, emotions and emotion regulation strategies, learner reticence and silence, motivation, self-concept and willingness to communicate.