Understanding the association between genotype and agronomically important phenotypes (early flowering, hard seed, and winter hardiness) will facilitate cultivar selection and inform breeding programs concerned with the cover crop hairy vetch (Vicia villosa Roth). We used molecular, observational, and biochemical techniques to identify and evaluate 64 accessions of hairy vetch that originated throughout the world and comprise the USDA National Plant Germplasm System. Time to flowering, percent C, and percent N were measured on plants of each accession grown in the field at Beltsville, MD. Amplified fragment length polymorphisms were assayed on each accession. We related parameters of genetic, phenotypic, and biochemical diversity to the geographical origins of the accessions. Country of origin explained little of the marker genetic diversity in this collection. Climate factors of geographical origins, however, explained larger amounts of the marker genetic diversity observed. These results provide baseline information to identify a core genetic subset of the V. villosa germplasm collection. Information presented here may facilitate future V. villosa breeding efforts and directly assist farmers in cover crop varietal selection.