Based on data gathered during a Young Lives research in the highlands of Vietnam, this paper examines children’s perceptions of similarities and differences between themselves and children from other ethnic groups, and the meanings they give to belonging to an ethnic group. Taking advantage of an approach that combines discursive analysis and the anthropological concept of agency, the paper highlights the cultural construction of children’s identities as well as children’s critical capacities. It is also an attempt, through exposing the dynamics of field interactions, to demonstrate the fruitfulness of a critical, self-reflective approach to the production of ethnographic knowledge.