Smallholders' sustainable development requires holistic attention to agri-food systems' interrelated environmental, economic, and social dynamics. This is especially true in developing countries where resource scarcity and vulnerability constrain farmers' challenging production realities as well as influence their well-being. Achieving sustainable development outcomes for African smallholders means agricultural research for development (AR4D) must adopt comprehensive quantitative methods that integrate relevant social factors alongside agronomic and economic analyses. However, AR4D has focused more on technical and market -oriented approaches, sometimes identifying social influences but often failing to conduct deeper, anticipatory social impacts analyses. This case study examines five smallholder -focused AR4D projects implemented over a decade in one region of Madagascar. Findings exemplify the need for social impacts analysis in practical terms, emphasizing where opportunities were lost to generate evidence for improving policy guidance. Transdisciplinary methods can help AR4D address this need so the authors propose an integrated approach to quantitative social impacts analysis, inspired by Life Cycle Thinking and the Social Life Cycle Assessment tool, to promote smallholders' sustainable development more effectively in research and policy.