Sustainable livestock production utilizing rangelands requires knowledge of the nutritional value of available forage and experience with the probable responses by livestock to the quality and availability of that forage. Supplementation research that started over 50 years ago has attempted to develop a predictive tool that could be used by ranchers. The goal of this publication is to expand on a scheme called Strategic Supplementation. By using this process, livestock are supplemented only during the most effective period, with the minimum potent amount, and in a practical delivery system. This publication will assist range livestock managers and nutritionists in making these supplementation decisions.