This paper examines the informational origin of the low adoption rates of modern agricultural technologies in smallholder agriculture in sub-Saharan Africa. It argues that a large part of these low rates can be explained by the fact that many smallholder farmers are unaware of the existence of these technologies. The paper analyzes the structure of the adoption gap resulting from this lack of awareness and presents a methodology for estimating that gap and the truly informative adoption rates and their determinants. This methodology is used to estimate the potential adoption rates and adoption gaps of New Rice for Africa (NERICA) and the determinants of NERICA exposure and adoption in four West African Countries: Côte d’Ivoire, Guinea, Benin and Gambia. The estimated adoption gaps of 21% in Côte d’Ivoire, 41% in Guinea, 28% in Benin and 47% in Gambia suggest that NERICA adoption could be increased significantly.