Productivity gaps for 321 groundnut farmers from Uganda and Kenya were analysed using data from the 2009 growing seasons. Farmers who planted improved varieties enjoyed output advantages of 143% in Uganda and 58.6% in Kenya over those who planted only local varieties. Farmers had a mean technical efficiency of 54.6% in Uganda and 54.4% in Kenya. No significant differences were found in the mean technical efficiencies of research and non-research farmers, and between maleand female-managed plots. Productivity therefore could be enhanced if high-efficiency households invest more in improved varieties and if low-efficiency households make better use of their existing technology. Continued development of improved varieties will further shift the production frontier outward. The apparent spill-over effect of the technical support received by research and nonresearch farmers suggests that farmer education has a multiplier effect. An improvement in extension service delivery could help to enhance the managerial skills of both farmer categories.