Malnutrition was one of the most significant children’s health issues of the early twentieth century, but it also engendered considerable controversy. Just how many children were truly malnourished, and how could they be reliably identified? Despite the failures of numerous diagnostic methods—even the definition of malnutrition defied consensus—health authorities remained convinced that malnutrition was a serious and widespread problem. Indeed, the imprecision that surrounded the condition allowed it to be used metaphorically to advance a broad range of professional, social, and public health agendas. By the 1940s, due in part to the lack of reliable diagnostic methods, public health nutrition policy shifted abruptly from one of assessment, based on mass surveillance and individualized care, to one of management, based on a universal program of nutrition education, fortification of foods, and food security that treated all children as in need of nutritional assistance.