The aim of this report is to contribute to a discussion on how to strengthen the evaluation practice of Norwegian aid. Norwegian aid authorities, in recent policy documents, emphasise the need for improved methods for assessing impacts of development aid. The issue is also one of setting sound and realistic objectives for aid. The report (1) reviews recent Norwegian aid evaluations with an explicit mandate to study impact, and assesses how the evaluators establish causal effects in their analyses, and (2) provides recommendations for how to improve the quality of aid impact evaluations.