In the 1950s, researchers devoted very little time to understanding breastfeeding, physicians and nurses learned almost nothing about it in their training, and even those mothers who showed an interest in breastfeeding often found the lack of information and support for doing so to be overwhelming. In this period, Niles R. Newton stands out for a number of reasons. Born in 1923, Niles went on to marry, have four children (all of whom she breastfed), earn a master’s degree and a PhD, and carry on a successful research career as a specialist in the psychology of childbirth, breastfeeding, and childrearing. Her unique work in the psychology and physiology of breastfeeding shed precious light on many of the most common problems that mothers faced when they set out to breastfeed their infants. Her research quickly became the cornerstone of the back-to-the-breast movement and was snapped up by breastfeeding advocates, mothers, and La Leche League, in particular, who helped popularize and disseminate Newton’s ideas to an eager audience. This article examines Newton’s life and works in more detail and argues for the central place she holds in the history of modern breastfeeding.