Relief agencies place increasing emphasis on ensuring that political analysis informs their programming in difficult environments. There is a greater recognition of the political origins of vulnerability. There is also greater recognition of the need to ensure that aid is delivered in a principled fashion, and is not used by belligerents to sustain violence. This paper summarises the findings of research examining how humanitarian organisations might better understand the political and economic factors that determine the vulnerability of conflict-affected populations. Based on case studies in Afghanistan, the Democratic Republic of Congo (DRC), Senegal and Sierra Leone, the research used an adapted version of the sustainable livelihoods approach to examine the origins and dynamics of vulnerability at the household and community levels.