Invasive plants may alter arbuscular mycorrhizal fungi (AMF) communities on which resident plants depend. To determine if the invader crested wheatgrass (Agropyron cristatum [L.] Gaertn.) associates with different AMF than resident plants, we compared AMF communities of six A. cristatum–dominated sites to five sagebrush steppe and three mixed-grass prairie sites in the Northern Great Plains. Consistent with findings on some other invaders, roots of A. cristatum were without AMF and supported fewer AMF operational taxonomic units than seven native species and two nonnative species. Restoring natives to A. cristatum sites is notoriously difficult. Our findings suggest a lack of soil mutualists may contribute to the difficulty.