Leguminous plants are represented by approximately 19,000 species in over 750 genera, and are economically second only to the grass family. Legumes are a valuable source of forestry products (timber, resins, etc.), various commercial chemical products (dyes, tannins, insecticides, etc.), edible 82grain (soybean among others), forage consumed by grazing animals or as hay, and plants in conservation systems for erosion control. Historically, forage legumes have played an important role in agriculture, and over 200 genera are considered to have commercial potential. Prior to the commercial production of inorganic fertilizers, they were widely grown for their contribution to soil fertility, either as part of a general soil improvement program or in specific crop rotations. The replenishing of organic matter in agricultural systems is crucial to soil conservation, particularly in areas of the tropics where fragile soil conditions and extremes of rainfall exist. The enhanced awareness of soil fertility maintenance and/or improvement as a component of ecologically based production systems should increase the use of legumes in many countries. As environmental concerns about the use of inorganic N fertilizer become more important worldwide, the use of forage legumes should once again become a significant and integral factor even in highly mechanized agricultural systems.