Technical Abstract: Thickspike wheatgrass (Elymus lanceolatus) is a native, autotetraploid (2N=4X=28), perennial grass characterized by its tolerance to drought and its rhizomatous growth habit. It is a desirable species for reseeding of degraded rangeland in the western U.S., but exhibits poor seed production and establishment ability. Improved seed production and rhizome spread, in conjunction, with forage production would enhance the performance of this species in reseeding efforts. This study included a group of half-sib families developed from the polycross of individuals from the cultivars Bannock and Schwendimar and analyzed their performance across two years at a location near Nephi, UT, U.S. Significant variation and heritability within the population and high transgressive segregants occurred for seed production and rhizome spread, but not for forage production. Additionally, there were no negative correlations between any of the traits. Thus, selection for increased seed production and rhizome spread within this population should prove successful but would not be successful for increased forage production.