Thermopsis divaricarpa (Fabaceae) is a common wildflower in the montane zone of the Colorado Rocky Mountains, but its reproductive ecology is still largely unknown. Montane meadows are recognized for their relatively high species richness and important ecosystem services. Thus, knowledge of the reproductive ecology of T. divaricarpa is useful when assessing community-level responses to climate change in the montane zone of the Rockies. We investigated the phenology, breeding system, and pollination of this species in the southern Rocky Mountains of Colorado. Our results suggest that T. divaricarpa flowers from early June to mid-July, exhibits a facultative xenogamous breeding system, and may be pollinated by bumble bees. Pollen grains of T. divaricarpa are singular, ellipsoidal, and tricolpate. Beetles consume floral tissue, but their role as pollinators is questionable.