This book focuses on ethical and methodological issues faced by researchers working with young language learners in formal school contexts. It uncovers and explicitly discusses a range of ethical dilemmas, challenges and experiences that researchers have encountered and grappled with, in studies of all kinds from large scale, experimental studies to ethnographic studies focused on just a handful of children. The chapters are written by researchers working with children in different classroom contexts around the world and highlight how ethical dilemmas and tensions take on a complex form in child-focused research, requiring researchers to pay particular attention to the social and cultural norms of the different communities within which children are educated as well as their school-based experiences. The book comprises three sections, with the first part focused on involving children as active participants in research; part two on ethical challenges in multilingual contexts and part three on links between teacher education and researching children. The book includes a critical discussion of the opportunities and challenges associated with applying the UNCRC (1989) document in second language research with children which will be of use to any researcher working in this area.