In 1942, the British Minister of Health commissioned a report from the newly established Advisory Committee on Mothers and Young Children into ‘What can be done to intensify the effort to secure more breast feeding of infants?’. To make their case, the members of the sub-committee put in charge of the report sought expert testimony on the benefits of breastfeeding. They consulted medical officers of health, maternity and child-welfare officers, health visitors, midwives, obstetricians, paediatricians and a physician in private practice. They also consulted five ‘psychologists’ (a contemporary umbrella term for psychologists, psychoanalysts and psychiatrists). It is not surprising that the committee turned to medical professionals, as infant feeding had long been an area of their expertise. However, seeking the views of ‘psychologists’ when establishing the benefits of breastfeeding marked a more innovative development, one which suggested that a shift in conceptualising the significance of breastfeeding was gathering pace. In the interwar period, psychoanalysts and psychoanalytically oriented psychiatrists showed growing interest in early infancy. It led to an extensive psychoanalytic engagement with contemporary feeding advice disseminated by the medical profession. This article will explore the divergences and intersections of medical and psychoanalytic theories on breastfeeding in the first half of the twentieth century, concluding with a consideration of how medical ideas on breastfeeding had absorbed some of the contentions of ‘psy’-approaches to infant feeding by the post-war period.