This dissertation examines the often-overlooked work of scientists investigating nutrition at land-grant colleges and agricultural experiment stations in the mid to far West, especially in Wisconsin and California, from 1887 to 1930. It challenges the historiography’s dominant narrative that nutrition science was exclusively laboratory-based and quantitatively-focused; that it was primarily a tool of social control; and that it was chiefly the work of scientists and reformers in the urban Northeast. Rather, I argue, chemists working at land grant colleges and experiment stations around the nation forged a holistic tradition of nutrition research that countered the reductionist views of the Northeast’s “pure” and industrial scientists and urban reformers. Chemists working in the agricultural tradition were skeptical of the ability of quantitative methods alone to assess nutritional value. They placed a value on taste, pleasure, and custom in their approach to nutrition and expressed caution over the use of new industrially-processed foods and preservatives. They were concerned not only for the health of consumers, but also about the impact of new industrial foods and food systems on their farming constituents. They worked assiduously for the passage of pure food and drug laws. Nutrition science itself was transformed by their pioneering vitamin experiments. Drawing on the archival papers of chemists investigating nutrition at the agricultural colleges and experiment stations in the Midwest and California, I trace the rise and fall of the agricultural tradition of nutrition science through five significant events in nutrition science in the United States from the 1880s to the 1920s. These events include the first USDA dietary surveys of the 1890s; the debates over pure food laws leading up to the Pure Food and Drug Act of 1906; precursors to and early vitamin experiments in the 1910s; the work of scientists in the U.S. Food Administration during the First World War; and food fortification research and university-industry partnerships at the University of Wisconsin in the 1920s. I explain how these chemists investigated nutrition questions, framed their understanding of healthful diets, and positioned their role in relation to farmers, consumers, processors, and government in the increasingly industrial food system throughout these events. Shifting the focus from nutrition workers and urban reformers in the Northeast to agricultural chemists in the Midwest and California, my dissertation also positions the development of the science in the changing agricultural landscape and industrializing food system. Finally, I show how this history challenges the linear narratives that have dominated the historiography, how it reveals an alternative possible trajectory for the science, and how it significantly shaped the development of nutrition science and its role in American society.