Technical Abstract: An effective germplasm collection provides genetic variation useful to crop improvement, botanical research and conservation of plant biodiversity. The USDA National Trifolium germplasm collection currently limits the collection's effectiveness in serving multiple uses. Reflecting the mandate of plant introduction, the collection is strongly biased towards the two major cultivated red and white clover species, which make up 56% of the collection. Although many wild species are represented in the collection representation is poor for species considered gene sources for the cultivated species and for species with minor uses. The objectives of this paper are to demonstrate how the collection can be diversified to better serve users and contribute to the conservation of the genus. Reflecting priorities proposed in the 1970's the scope was defined as containing all species within the genus Trifolium. Next a broad gene-pool model was defined on the basis of ease of intraspecific hybridization and the history of crop use. Areas in the model were then identified that required more accessions to represent diversity of specific interest to users, or that were vulnerable to erosion or extinction.