Over the past three decades the development of agricultural research staff in sub- Saharan Africa has been impressive. There were significant increases in the number of researchers (a sixfold increase if South Africa is excluded), in Africanization (from about 90 percent expatriates in 1961 to 11 percent in 1991), and in education levels (over 60 percent of national researchers held a postgraduate degree in 1991). Developments in agricultural research expenditures were less positive. After reasonable growth in spending throughout much of Africa in the 1960s and early 1970s, growth largely stopped in the late 1970s. Donors have been dominant and increasing sources of support for agricultural research in Africa; their share of total agricultural R&D funding (excluding South Africa) grew from 34 percent in 1986 to 43 percent in 1991 -- 49 percent in 1991 if the large and largely locally funded Nigerian system is also excluded. Moreover, an analysis of government spending patterns provides evidence that many of the countries throughout Africa have shifted public investment priorities away from agricultural research. But these overall patterns of development mask important differences between countries and among institutions within countries and these differences have real policy consequences. Many of the developments of the past decade in personnel, expenditures, and sources of support for public-sector R&D in Africa are not sustainable. The rapid buildup of research staff is not paralleled by an equal growth in financial resources. Spending per scientist has continuously declined during the past 30 years, but most dramatically during the 1980s. Resources are spread increasingly thin over a growing group of researchers, which has negative effects on the efficiency and effectiveness of agricultural research.