Nonpoint nutrient pollution of water and soils remains one of the most significant environmental problems facing the USA today, despite decades of effort by scientists, state and federal agencies, and the agricultural and environmental communities. Concerns about nutrient impacts on environmental quality first began to emerge in the 1960s and initially focused on agriculture's role in nitrate contamination of ground waters. In response, scientists, working mainly through universities, began research and extension efforts to improve N management. However, as national efforts to reduce point source pollution, particularly from municipal sewage treatment plants, intensified in the 1970s, the widespread nature of agricultural nutrient pollution became increasingly apparent. The importance of soil erosion in nonpoint Phosphorus (P) water pollution became more widely recognized and national efforts to prevent soil loss by conservation tillage and “Best Management Practices” (BMPs) expanded. During the 1960s and 1970s a fundamental change also began to occur in animal-based agriculture, as Animal Feeding Operations (AFOs) concentrated geographically, resulting in regional excesses of manure and nutrients relative to available land bases. This led to national programs to improve the management of animal wastes. Water quality monitoring expanded in the 1980s and began to document the scale and geographic locations of water bodies where pollution was linked to agricultural nutrients. Concerns about nutrient effects on air quality and human health, particularly ammonia-N and N oxides, emerged. Together, these problems led to increased federal funding for research focused more on the environmental impacts of agriculture than on crop production. By the early 1990s, major national initiatives were being implemented by the U.S. Department of Agriculture to enhance local efforts to prevent nutrient pollution of ground and surface waters. These efforts were supported by a growing body of research from university and government scientists on the causative factors and BMPs needed to minimize the impact of agricultural nutrients on environmental quality. Major improvements occurred in our ability to quantify soil erosion and identify N-responsive soils through soil testing. Research also showed that soil erosion was not the only factor impacting nonpoint P pollution of surface waters. The buildup of P in soils from long-term over-fertilization or excess manure applications raised questions about dissolved P transport to surface waters. This led to the national development and widespread adoption of a risk assessment protocol for field-scale P loss to water (the P Index). In response to major failures of manure storage facilities at AFOs in the mid-1990s, the U.S. Environmental Protection Agency developed regulations to control pollution from concentrated AFOs. USDA developed comprehensive guidance for nutrient management on crop and animal operations. At the same time, major environmental problems in several U.S. states, such as fish kills, decreased biodiversity and habitat, and toxic algal blooms resulted in the rapid passage of state nutrient management laws restricting use of manure, fertilizer, and sewage sludge. By the early part of the 21st Century, USDA state offices had developed and implemented guidance on nutrient use. A few states passed more restrictive nutrient management laws, even extending to non-agricultural sectors (e.g., golf courses, urban lawn care). Recently, at the federal level, the focus has increasingly been on specifically demonstrating how voluntary and regulatory programs are improving environmental quality. This presentation critically analyzes the roles scientists played in the development of national and state-level nutrient management policies. We also look to the future and present recommendations on how scientists can most effectively participate in improving nutrient management policies that protect and restore environmental quality.