Scientific plant improvement dates from the beginning of the twentieth century. Application of the principles of selection and breeding to the rice plant yielded modest results in the period up until the 1950s. In the following decade, breeders working in Southeast Asia focused their attention on a new plant ideotype - the semi-dwarf rice type. 1 Earlier improved rices out-yielded farmer’s selections by 10-20%, but the productivity gains with semi-dwarf types were much greater. In some cases yields were doubled or trebled. The uptake of semi-dwarf varieties by farmers in better-favored environments of South and Southeast Asia was dramatic during the 1960s and early 1970s. The resulting leap in productivity was dubbed the “Green Revolution.�? Development agencies then set about the task of replicating the technical success of the Green Revolution in other humid tropical regions. Despite concerted attempts to introduce the new rice technologies to small-scale farmers through integrated agricultural development projects in the 1970s and 1980s, success in Africa’s traditional rice regions has proved especially elusive. The present chapter, a case study of rice research and its impact in the nodal country of the West African rice region - Sierra Leone - is an attempt to assess some of the strengths and weaknesses of the Green Revolution approach to plant improvement in Africa, and to consider alternatives.