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Because of water and nutrient limitations, vegetation production on rangelands is lower than other ecosystems that are being considered for biofuels production. Some rangelands simply do not have the production potential to be considered. Higher production rangeland regions, such as the Southern Great Plains (SGP) of Texas and Oklahoma, Tallgrass Prairie, or certain juniper-dominated areas in the Intermountain West may have biofuel potential, but these bioenergy sources should be viewed as secondary rather than primary because annual production is not sufficient for a sustainable bioenergy production operation. Our data from Texas indicates that honey mesquite (Prosopis glandulosa), a multi-stemmed woody legume, may have potential as a biofuel source because it overcomes nutrient deficiencies due to N-fixation, is drought tolerant, has relatively high regrowth potential following above-ground harvest, requires little post-harvest drying and has high energy content. We have described a bioenergy harvest system that considers total system land area required and regrowth harvest frequencies. Above-ground harvest methods that allow regrowth to be harvested are economically much more viable than whole plant extraction. Periodic mesquite harvest in selected patches (i.e., “brush sculpting”) will result in ecosystem restoration via increased grass production, reduced soil erosion and increased structural diversity for wildlife habitat. Impacts of large scale harvesting of mesquite on other ecosystems services, such as wildlife habitat will be discussed. Mesquite appears superior to switchgrass and sorghum biofuels in GHG offset efficiency and GHG use efficiency once land use change effects are accounted for. Mesquite production on a per-land area basis is lower than these other feedstocks and therefore could not supplant them entirely, but may be suitable as a complementary feedstock to contribute to total biomass feedstock demand. A combination of planted switchgrass areas near mesquite (or juniper) clusters may provide the most optimal rangeland bioenergy option.