The present study assesses the impact of a rural development project on farmers' livelihoods, as perceived by farmers, development organization staff and researchers. The project concerned, aimed to increase small-scale farmers' financial benefits by promoting the commercialization of Ricinodendron heudelotii (Baill.) Pierre ex Pax kernels (njansang) in Cameroon. The three parties evaluated the impacts of the project, over the 2005-2010 period, through indicators embedded in the Sustainable Livelihood Framework (natural, financial, human, social and physical assets). Project households were compared with control households.Results show that farmers' and development organization staff's views were aligned regarding the relative importance of the indicators to measure success (with overlaps > 85%). The three stakeholders evaluated changes of farmers' livelihood indicators over the 2005-2010 period on 5-point Likert items. All three stated that most indicators improved significantly more in project than in control households (p < 0.001). Development organization staff probably overestimated changes induced by project interventions as they perceived significantly larger changes as compared with farmers and researchers (p < 0.05). Our study highlights the differences between impact perceived by farmers, development organization staff and researchers and helps to build the knowledge base of the potential and reliability of participatory evaluation approaches. Furthermore, an approach to assess impacts on people's livelihood is proposed, combining the strengths of participatory evaluation with those of classic evaluation methods.