In recent years, child-centered research has garnered increasing attention among scholars working with children. However, it remains under-explored within the field of applied linguistics. This gap is partly attributable to the conceptual complexity of the notion itself; "child-centered research" encompasses multiple interpretations, and each significantly shapes research design and implementation. This edited volume offers a collection of reflective essays by leading scholars in the field of additional language learning and teaching with children. The contributors draw on their own research experiences to explore the complexities, ethical dilemmas, and methodological challenges they have encountered. They also propose future directions for the field, emphasizing the importance of engaging more deeply with child-centered approaches. By bringing together voices from diverse research traditions, this book aims to provoke critical discussion and inspire new thinking about research ethics and methodologies among researchers, teacher educators, and postgraduate students alike.