Children's status as research participants in applied linguistics has been largely overlooked even though unique methodological and ethical concerns arise in projects where children, rather than adults, are involved. This article examines the role of children as research participants in applied linguistics and discusses the limitations of traditional research "on" and "about" children, using research studies as examples published in mainstream applied linguistics journals. As neighbouring fields have already embraced a new approach to children as "active participants", it is essential that SLA also widens its research agenda by focussing on children as active social agents who are capable of taking more responsible roles in research that concerns their own language learning. The last section of the article examines studies "with" and "by" children outside SLA in some detail and suggests future directions for research within SLA, based on the epistemology of plurality and on developing a dialogic relationship between adult facilitators and children.