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Our understanding of the impact of herbivory on vegetation dynamics is primarily based on livestock grazing, while herbivory by native wildlife, such as prairie dogs, is not well understood. Extensive prairie dog populations on the Standing Rock Indian Reservation limit forage availability for livestock; however, control measures may be limited because of 1) the cultural importance of prairie dogs to the Lakota society, 2) concerns about impacts to associated species such as black-footed ferrets, and 3) potential losses to plague. Therefore it is critical to understand vegetation dynamics of mixed-grass prairie systems grazed by both cattle and prairie dogs to predict herbivory impacts on important plant species and develop management strategies for coexistence of livestock and wildlife. A key initial variable was selection of stocking rate strategy to account for both cattle and prairie dog grazing. We based initial stocking rates on previous research indicating each prairie dog-occupied acre provides 50% of the forage of each non-occupied acre. Utilization data determined that our stocking rate strategy was effective in producing predicted utilization levels. Other efforts are focused on evaluating differences in cattle and prairie dog grazing and the consequences of that grazing to facilitate improved prediction of outcomes of grazing for important plant species. These efforts include 1) determining the probability, frequency, and severity of grazing of western wheatgrass tillers by cattle and by prairie dogs; 2) western wheatgrass plant responses to those defoliation patterns, including tiller initiation and survival, bud banks and bud survival, and tiller reproduction strategies; and 3) the presence, size and viability of seed reserves.