This Working Paper describes how key concepts of the Sustainable Livelihoods (SL) approach were incorporated into methods for assessing the impact of wildlife projects in East Africa. It shows that the SL approach can be applied not only to planning new projects, but also to the review of existing ones –even where these were not planned with SL concepts in mind. The working paper explains the rationale for developing an impact assessment methodology incorporating livelihood analysis, summarises the methodology and its application, and identifies several lessons learnt for application of SL approaches.