Abstract: This study explored how social heterogeneity influenced the performance of three specific development projects, namely Western Kenya Community Driven Development and Flood Mitigation Project, National Agricultural and Livestock Extension Programme & Small Dairy Commercialization Programme within Lugari, Kakamega County. Many studies have raised alarm on the poor performance of donor funded projects and have advanced different reasons as being responsible and so is this study. The findings from this study aim at providing insight into the subject of study and furthermore add new knowledge to the existing body in the field of social development and more specifically on the place of social interactions.