There is growing interest by development scholars to revisit the inverse farm size-productivity (IR)
hypothesis to guide policy on land and agricultural development strategies. However, it is remarkable that
existing empirical studies, particularly in sub Saharan Africa (SSA), have been derived from data with
few farms outside the zero to ten-hectare range, yet their findings have been extrapolated beyond this
range. Moreover, the definition of productivity has mainly been limited to yield or other land productivity
measures to explore this highly contested hypothesis. Using data from Zambia, this study addresses these
shortcomings and explores the reasons for potential differences in productivity within and between farm
size categories, so as to provide practical guidance for relevant policy formulation. Results from our
carefully constructed measures of productivity -- accounting for all production costs including less
commonly considered costs such as family labor and fixed costs -- reveal that the farm size-productivity
relationship is not uniform across the four measures of productivity. While relatively large farms
(medium-scale farms) enjoy labor productivity efficiency, they do not exhibit a superior efficiency
advantage over small farms when other productivity measures are considered. With a multiple set of
considerations to be made in setting land and agricultural policy, these findings indicate that prioritizing
unutilized land for medium- over small-scale farms on efficiency grounds are unwarranted.