The fact that obesity has become a distinctive modern problem is a familiar historical finding. Traditional societies inevitably had to pay far more attention to issues of food adequacy and undernutrition than to the results of overindulgence. Obesity might be noted as a product of individual gluttony, but it was not a common threat. In Western societies, both in Europe and North America, the move toward a greater awareness of the dangers of overweight began to take shape toward the end of the 19th century and picked up momentum from that point onward. This chapter focuses on the decades of transition – into the mid-20th century – when concern about overweight and obesity began to reach not only the wider public, but also a growing array of medical practitioners.