This Study was commissioned by the OECD/DAC Expert Group on Aid Evaluation. Its primary purpose was to undertake a synthesis study of the impact of Non- Governmental Organisation (NGO) development projects, derived largely from evaluation reports, as well as the methods used in assessing impact. The information was gathered from evaluation reports commissioned by donors, and from data and information gathered (through reports and interviews) in 13 case studies, undertaken in both donor and southern countries. The primary focus of the Study was on the impact of discrete development interventions in poor countries; some attempt was made to include projects focusing on capacity-building and linked initiatives, but the database of such projects is still very small.