Technical Abstract: Dietary intervention studies of human subjects produce valuable information regarding dietary effects on biological processes and risk factors for chronic diseases. Using the well-controlled feeding approach, volunteers consume only foods that have been precisely prepared in a research kitchen, whereas in behavioral counseling studies participants self-select their foods within guidelines. Because controlled feeding studies meticulously control experimental diets, they are intellectually and logistically challenging to conduct. They afford exciting opportunities for nutritionists in designing protocols, developing budgets, and collaborating in multi-disciplinary research teams. Food composition data and chemical analysis of menus are used to prepare research diets with precision. Dietitians determine the energy requirements of subjects and adjust diets as required, most often for weight maintenance, throughout the study. Researchers must be cognizant of the ethical treatment of the study participants while motivating them to adhere to the protocol requirements. Nutritionists possess many of these talents, but may require training specific to well-controlled feeding studies. Training and information related to the conduct of controlled feeding studies has recently become more accessible. For nutritionists already participating in the conduct of dietary studies and others who wish to increase their knowledge of research, we provide an overview of well-controlled feeding study methodologies, proficiencies for planning and implementing these studies, and training resources.