Previously, most studies in this area have focused on the reciprocal effects of language teachers' emotions, identity, well-being and agency, with emotions often being portrayed as consequential entities. However, this book advances the field by exploring specifically how language teacher emotions can be used as tools for personal and professional development. The authors provide empirical, theoretical, conceptual and practical contributions which demonstrate how emotional responses provide data that can be analyzed and reflected upon and how emotions can be seen not as occurrences that are suffered, but as actions, judgments, choices, responsibilities and data that can be used to improve personal growth and professional lives. The chapters shed light on the potential of emotions as tools for teachers' personal and professional development, such as, but not limited to, emotional literacy, emotional intelligence, emotional agility and regulation, emotional memory and self-exploratory and self-reflective inquiries.