We review the literature on the distribution of farm sizes in sub-Saharan Africa, trends over time, drivers of change in farm structure, and effects on agricultural transformation, and present new evidence for six countries. While it is widely viewed that African agriculture is dominated by small-scale farms, we show that medium-scale farms of 5 to 100 hectares are a non-trivial—and rapidly expanding—force which is influencing the nature and pace of food systems transformation in many countries. The increased prevalence of medium-scale holdings is associated with farm labor productivity growth and underappreciated benefits to smallholder farmers. However, the rise of African investor farmers may also be contributing to escalating land prices and restricted land access for local people. A better understanding of these trends and linkages, which requires new data collection activities, could help resolve longstanding policy debates and support strategies that accelerate agricultural transformation.Please note: This paper is available to download upon free registration with SSRN. See link under 'More details' below.