Plants belonging to the family Fabaceae (or Leguminosae) are characterized by their ability to form a symbiotic relationship with soil bacteria called rhizobia contained within root nodules which fix atmospheric nitrogen which can be used by the host plant (although not all legumes fix nitrogen). This nitrogen-fixing ability presents considerable benefits to plants growing in nitrogen-constrained environments and lends them various functions of potential benefit to humans who utilize them for various livelihood purposes. Legumes as a plant family are diverse in structure ranging from herbaceous plants through to woody shrubs and trees. This diversity of form and function presents multiple opportunities for beneficial human use but also complexity in terms of how different legume species fit within different farming systems. The science community, recognizing the potential benefits of increasing legume use in smallholder farming systems in Africa have been enthusiastic in their promotion of legumes among farmers but the reality on the ground is that legume uptake is much lower than expected. The reasons for this lack of legume uptake have been eloquently reviewed before (Sumberg 2002) and mainly relate to an inadequate understanding among legume promoters of the livelihood realities of the African smallholder farmer. It is with this in mind that the Legume CHOICE decision support approach is being developed. Legume CHOICE offers a systematic framework for categorizing legume species, defining how they fulfil different livelihood functions and then matching appropriate legume types to widely varying farming contexts. The following narrative expands on a series of Concepts and Definitions before describing the logical flow of Legume CHOICE activities