The objective of this review is to provide an integrated historical account of the complex, often convoluted events impacting milk hygiene and its resultant effect on infant mortality from 1875 to 1925. Heat pasteurization of cow's milk is necessary for rendering this important nutrient source safe for humans-particularly infants. Developed by Louis Pasteur in 1864, pasteurization evolved from the commercially important parboiling of wine and beer when the Industrial Revolution was effecting rapid societal change in Western societies. In European and American societies of the early and mid-19th century, infant mortality rates were 30- to 60-fold higher than the current rates of five or six deaths per 1,000 live births per year. With proof of the germ theory of disease came convincing evidence of the role of microbes in the transmission of infections, which led to the discovery that microbial pathogens were transmissible via milk. Diseases caused by milkborne pathogens include human and bovine tuberculosis, brucellosis, salmonellosis, streptococcal infections, diphtheria, and "summer diarrhea." With pasteurization of milk, infectious diseases with their high infant mortality rates decreased by only half by the early 20th century, despite concurrent medical and dairy hygiene advances. To further mitigate unacceptably high infant mortality rates, social support providers-including public health nurses and midwives-encouraged breastfeeding, especially among socioeconomically disadvantaged mothers. Improvements in pulsating vacuum milking machines also favorably impacted food safety by providing a clean, enclosed environment. Currently, bottle feeding still competes with breastfeeding as the preferred method, and the sale of raw, unpasteurized milk remains a contentious issue. Informed and responsible food safety professionals, physicians, and public health officials currently view breastfeeding as the preferred feeding method and milk pasteurization as the safer and more prudent alternative.