A great deal of attention is now paid to the ethics of social research. Research governance has expanded, and a burgeoning literature describes the processes, practices and questions that arise in social research with children, families and communities. This paper outlines the approach taken to research ethics within Young Lives, a longitudinal study of childhood poverty in Ethiopia, Andhra Pradesh (India), Peru and Vietnam, co-ordinated by a research team based in the UK. Drawing on fieldwork reports, qualitative data and other material, I offer some 'real life' examples of ethics questions encountered in research, providing insights into the experiences of fieldworkers. The paper emphasises the importance of understanding local contexts in undertaking research with children and families in environments that change rapidly, economically, environmentally and politically. Overall, my aim is to contribute to current debates about research practices, the ethics of longitudinal research with children, and research with children and parents in developing countries.