This paper synthesizes the findings of 22 micro-level studies on technology adoption carried out by the International Maize and Wheat Improvement Center (CIMMYT) with national agricultural research systems in Ethiopia, Kenya, Tanzania, and Uganda during 1996-1999. The authors found that technology adoption is taking place across Eastern Africa but considerable scope remains to improve the productivity of smallholder agriculture in higher potential regions with high levels of adoption. Extension was the variable most highly correlated with technology adoption, and extension services continue to play an important role in disseminating information on new varieties and how to manage them. Despite the usefulness of the micro-study results, especially for priority setting and impact assessment, future adoption studies can be improved by standardizing definitions across studies and using sampling techniques that allow results to be generalized across wider areas. Finally, the paper suggests that maize and wheat breeding research should be made more relevant to the preferences and circumstances of farmers, that the link between research and extension should be strengthened and include the private sector and non-governmental organizations, that policies should support the development and expansion of efficient markets for inputs and outputs, and that rural credit systems should be strengthened.