Most of the world's hunger and poverty occurs in rural areas. The use of fertilizers could improve agricultural productivity in these areas. However, many developing countries attach a low priority to the subsistence/smallholder sector, particularly in disadvantaged areas. Properly applied, fertilizer use is sustainable, not only improving agricultural productivity but also helping to avoid land degradation. Incorrectly used, fertilizers may be harmful. In order to assess the present and potential efficiency of fertilizer use, it is necessary to know, for each agro-ecological region of each country: the crops on which fertilizers are being used; the social and structural context; appropriate fertilizer application rates; the profitability of fertilizer application at these rates; the arrangements for supplying fertilizers to farmers and for marketing their produce; the credit facilities available to farmers and distributors; whether sufficient research on appropriate fertilization techniques is being carried out; and whether the resulting information is reaching the farmers. This publication reviews these various issues, substantiated by examples from each country, and analyses available statistics on fertilizer use by crop.