The Green Revolution’s objective of increasing yields precipitated an approach to impact evaluation that relied predominantly on econometric analyses to measure yield differences and how those differences impact farmer incomes. This paper explores the legacies of this assessment scholarship for New Breeding Technologies (NBTs) in sub-Saharan Africa. It examines three pervasive assumptions underpinning econometric-informed evaluative approaches: farmer homogeneity, profit maximization, and scale neutrality. The paper concludes by introducing Farming Systems Research as a complement to existing econometric approaches, which can serve to create more robust and accurate assessments of the potential farm-level benefits and challenges of NBTs in sub-Saharan Africa.