Drawing on the experiences of the members and observer organisations of the Development Assistance Committee Network on Development Evaluation (EVALNET), this study provides a snapshot of the core elements and ways of working within development evaluation systems. It offers insight to development co-operation organisations as they seek to establish or strengthen credible evaluation systems of their own, to support learning and accountability. The report also explores the role of evaluation in development co-operation and humanitarian assistance, including the various policy and institutional arrangements used with evaluation systems. It then reviews the evaluation process, from deciding on evaluations to disseminating findings and finally, focuses on how evaluation findings are used to improve development co-operation efforts.