Technical Abstract: Although western wheatgrass [Pascopyrum smithii (Rydb.)] is an important perennial grass species for agriculture and conservation management in central and western North America, its lack of seed production and seeding vigor limits its effectiveness. To address the weaknesses, a study was conducted to assess rhizome spread, seed production, seed weight, germination percentage, and emergence rate of seed produced from 48 western wheatgrass cultivars and germplasm accessions at a field site near Nephi, UT, USA during 2007 and 2008. The western wheatgrass cultivars had approximately two times higher seed production than the germplasm accessions during both 2007 and 2008 and also had higher seed weight in 2007 and emergence rate in 2008. The germplasm accessions had higher seed weight in 2008. For the remaining traits, there were no differences among the different germplasm sources. Based on principle component analysis, a subset of cultivars and germplasm accessions with high seed production and emergence rate was identified that could be used to produce improved cultivars and germplasms. There was little evidence of strong relationship between geographic, genetic, and phenotypic distances among the various lines examined. Additionally, based on genetic marker data, a subset of lines was grouped into three populations. Based on these results, selection among lines could occur to maximize agricultural performance regardless of site of origin, or within population selection could be practiced to meet conservation goals of minimizing hybridization among populations.