This article contributes to emerging discussions of child participation in general, and in research with migrant and displaced children specifically, by examining the involvement of children as research advisors in two projects: a study of foster care for separated children in Rwanda, and an analysis of the conditions of children outside parental care living in institutions and communities in Bangladesh. The comparison highlights the importance of conceiving participation as a research strategy, and advocates a ‘methodology of participation’ that considers varieties of participation and varieties of social change. Teaching research methods to children acting as advisors enabled them to understand what research is and to learn about the lives of other children, while contributing to decision-making processes in selecting questions, participants, interpreting findings and making recommendations. Children's input into research contributes to overcoming essentialist conceptualisations of children in difficult circumstances, and moving to viewing these children as social actors embedded in complex relational processes. At the same time, involving children in an advisory capacity considers them as active participants in the research process, as they are in social life