I investigated the individual and joint effects of simulated herbivory and interspecific competition on survival of Coleogyne ramosissima Torr. (blackbrush) seedlings. Seeds of C. ramosissima and Bromus rubens L. (red brome grass) were collected at mid-elevations (1220 to 1770 m) of the Spring Mountains in southern Nevada. A pot trial experiment was conducted for six months (27 wk) in a controlled environmental greenhouse. This trial experiment, consisting of a 2 × 2 factorial design with simulated rodent herbivory and interspecific competition with B. rubens as the main effects, resulted in four treatments. Herbivory on C. ramosissima by heteromyid and non-heteromyid species of rodents was simulated by clipping the top 3 cm of young shoots. Significant interaction was detected between herbivory and competition for C. ramosissima seedling survival. When herbivory and competition were examined independently, both factors had significant adverse effects on C. ramosissima seedling survival, with the former having greater negative effect than the latter. Results of this study suggest that simulated rodent herbivory and B. rubens competition limited survival independently, and that a combination of herbivory and competition caused synergistic reductions in C. ramosissima seedling survival. Understanding the role of herbivory and plant competition in reducing survivorship of seedlings is crucial to the management and regeneration of C. ramosissima shrublands in the Mojave Desert.