This paper presents the results of the analysis of policy changes that occurred during and after the implementation of the Smallholder Dairy Project (SDP) in Kenya, a research and development project which changed its focus towards achieving a greater impact from their findings on policy makers. It is a remarkable story of evidence-based policy making. The highly collaborative project was implemented by government institutions and an international research centre, later working together with advocacy CSOs. The high-quality, credible and relevant research results pinpointed a basic problem in dairy development in Kenya: the need to recognise and develop the informal sector that markets the vast majority of milk in Kenya. Although the resulting changes in national policy are still in the legislative process, changes in attitude and behaviour of key actors toward the informal milk market can be observed from national level down to local level.