In recent years, there has been increased interest in understanding how donor interventions in situations of fragility and conflict can contribute tot he processes of statebuilding. While external actors cannot determine the outcome of those processes, they can target their assistance to support positive statebuilding dynamics. Donors must ensure that they "do no harm" and consider both the intended and unintended consequences of their interventions. This publication fills an important knowledge gap by addressing two fundamental questions: what are the negative impacts that donor interventions can have on statebuilding; and what measures should donors adopt to avoid negative impacts on statebuilding processes? Do No Harm argues that the challenges of statebuilding are such that donors must develop a sophisticated understanding of political processes, patterns of state-society relations and sources of legitimacy in the countries where they are oeprating. Based on an extensive literature review and on six country case-studies (Afghanistan, Bolivia, the Democratic Republic of Congo [DRC], Nepal, Rwanda and Sierra Leon), Do No Harm offers a valuable addition to our knowledge on statebuilding in situations of fragility and conflict.