Oxfam, in partnership with Save the Children, conducted a series of annual surveys of the effectiveness of NGO relief efforts in northern Sri Lanka. Men, women and children were interviewed in depth and their perceptions and criticisms were recorded. The results of these surveys were used to inform and improve the relief programme, to make it more responsive to the needs of the displaced communities. This paper offers a critical assessment of the project, describing the methodology, assessing the outcomes and identifying lessons for other agencies interested in conducting similar participative, longitudinal studies.