This book argues that teachers of multiple languages (TMLs) form a distinct group of language teachers and that the study of this largely overlooked demographic group can reveal new insights into how we perceive and research language teachers. The book highlights the narratives of three TMLs from diverse global contexts, examining their journeys in navigating their careers as well as traversing multiple worlds and developing additional ways of being through new identities, beliefs and emotions. The author offers new, globally-relevant insights for language teaching research at individual, pedagogical and institutional level and demonstrates that teaching multiple languages is an emerging transnational phenomenon that cuts across age, languages, countries, institutions and career stages. By furthering our understanding of why and how some multilingual language teachers have expanded and changed their careers through teaching additional languages, the book offers a new perspective on how language teaching careers are changing in an increasingly globalized, multilingual world.