This paper examines the farm size and productivity relationship using data from Nigeria. The household data used has been drawn from a baseline survey conducted in Nigeria and financed by the Bill and Melinda Gates Foundations (BMGF).The relationship between farm size and productivity has long been a topic of debate in development economics. Using a cross sectional baseline data, we aimed at examining the relationship between maize yield and farm size across the selected agro-ecological zones. Specifically, it aimed at investigating the farm size–productivity relationship and its underlying determinants for maize producers in Nigeria. Findings from this study indicate that productivity measures are consistently highest among farms small farms, next highest among medium, and lowest among large farms. Gross profit per hectare and net profit per hectare on small farms are over 15% higher and 40% respectively higher than medium and large farms. The study further reveal a strong negative relationship between the value of output per hectare and own cultivated area with a doubling in cultivated area associated with a 35% or 98% decrease in the value of crop output per unit of cultivated land at the holding- or plot-level, respectively. We therefore recommended that farm size– productivity relationship and its determinants in developing countries like Nigeria should continue to be of interest to policy makers seeking to resolve the small-sized farm issue.