Our expanding population is demanding more productivity and other contributions from our rangelands. Range science is concerned with the plants, animals, soils, and waters on rangelands, particularly the interaction of these factors. Native plant communities should only be used as guides to determine site potential. Extensive practices on rangelands include manipulation of animals and burning. Intensive practices include control of unwanted plants, revegetation, and fertilization. When properly conducted, intensive manipulation practices often result in much higher production than before treatment. Each land manager determines the desired level of productivity based on economic, cultural, political, and social factors, and the availability of technology. The most effective method for control of unwanted plants varies with the sites, the species, and the degree of infestation. Revegetation may be required where desirable vegetation has been depleted by past grazing abuses, droughts, and encroachment of unwanted plants. Water is generally the primary factor limiting plant growth but when that need has been satisfied, additional plant nutrients such as nitrogen and phosphorus may be useful. The more costly practices are riskier and require higher management inputs, but the potential benefits are great. With changing technology or favorable economic conditions, the range manager may decide to intensify his range improvement efforts.