K-12 international education has gained increasing attention in internationalization. This introductory chapter provides a comprehensive overview of this emerging phenomenon. First, it synthesizes current scholarly literature, examining various definitions, theoretical approaches, policy contexts, and historical backgrounds used to analyze K-12 international education in a global context. It then explores specific topics emerging from critical scholarship, shedding light on the debates that shape critical approaches to K-12 international education. Themes such as global-local dynamics, the impact of geopolitics, ethics, and decolonization are examined, revealing tensions in policy and practice. Institutional theory, focused on values and norms, is used as a helpful guide that allows a better understanding of the country-specific differences emerging from the literature. The chapter highlights the need for further research and critical debate for deeper insight into the complexities and tensions arising from various national contexts. It concludes with an overview of the book’s chapters, which contribute to the ongoing scholarship in this field.