We, as editors, are pleased to introduce this book, which serves as a scholarly platform for a collection of research papers exploring the significance of Language Teacher Psychology and emphasizing the crucial role of teachers. The study of language teacher psychology delves into the psychological factors that impact the teaching and learning of a second language. This includes examining the attitudes, beliefs, and emotions that language teachers hold, as well as the influence of these factors on their instructional practices. In language learning, teachers play a crucial role in shaping students' attitudes, motivation, and engagement. Thus, it is essential for language teachers to possess a thorough understanding of both the language they are teaching and the psychological factors that impact language learning. Key factors that can affect language teacher psychology include their language learning experiences, cultural and individual beliefs, and their sense of efficacy in the classroom. Understanding these factors can assist language teachers in creating a positive learning environment that enhances students' language acquisition and success. In spite of the indispensable role that teachers assume in the realm of education, the majority of research in language learning psychology has predominantly concentrated on learners. Such neglect of teachers' psychological dimensions is tantamount to overlooking the needs of learners themselves. The psychological aspects encompassing teachers' well-being, resilience, motivation, and other influential factors are of utmost significance. In essence, the impact of teachers cannot be understated. The objective of this book is to offer a distinctive platform, uniting research endeavors pertaining to the psychology of language teachers, thereby providing a forum for their contributions to be heard. As editors, our primary objective is to comprehensively address an extensive array of topics pertinent to teachers, including emotions, agency, identity, burnout, self-concept, and self-efficacy. This book represents the culmination of a collaborative endeavor involving scholars from diverse regions across the globe. We extend our sincere gratitude to the reviewers, members of the international editorial board, the publisher, and those involved in the technical aspects, as this book is a testament to their collective efforts. It is a product of teamwork, and we express our appreciation to all who contributed throughout each stage of its development. We trust that the research papers contained within this book will provide valuable insights and captivating reading material for you.