Rickets, a childhood disorder that causes soft and misshapen bones, transformed from an ancient but infrequent threat to a common scourge during the Industrial Revolution. Factories, mills, and urban growth transformed the landscape. Malnutrition and insufficient exposure to sunlight led to severe cases of rickets across Europe and the United States, affecting children in a variety of settings: dim British cities and American slave labor camps, moneyed households and impoverished ones. By the late 1800s, it was one of the most common pediatric diseases, seemingly an intractable consequence of modern life. offers the first comprehensive history of this disorder. Tracing the efforts to understand, prevent, and treat rickets—first with the traditional remedy of cod liver oil, then with the application of a breakthrough corrective, industrially produced vitamin D supplements—Christian Warren places the disease at the center of a riveting medical history, one alert to the ways society shapes our views on illness. Warren shows how physicians and public health advocates in the United States turned their attention to rickets among urban immigrants, both African Americans and southern Europeans; some concluded that the disease was linked to race, while others blamed poverty, sunless buildings and cities, or cultural preferences in diet and clothing. Spotlighting rickets’ role in a series of medical developments, Warren leads readers through the encroachment on midwifery by male obstetricians, the development of pediatric orthopedic devices and surgeries, early twentieth-century research into vitamin D, appalling clinical experiments on young children testing its potential, and the eventual commercialization of all manner of vitamin D supplements. As vitamin D consumption rose in the mid-twentieth century, rickets—previously a major concern for doctors, parents, and public health institutions—faded in its severity and frequency, and as a topic of discussion. But despite the availability of drugstore supplements and fortified milk, small numbers of cases still appear today, and concerns and controversies about vitamin D deficiency in general continue to grow.   Sweeping and engaging, illuminates the social conditions underpinning our cures and our choices, helping us to see history’s echoes in contemporary prescriptions.