The way mothers feed their babies is, internationally, the subject of research, health policy initiatives, and popular discussion, which commonly affirm the mantra 'breast is best'. On one level, this mantra reflects scientific evidence about nutrition and maternal and infant health. From a socio-cultural perspective, the pro-breastfeeding message has, however, been considered an aspect of morality, which influences maternal identity in important ways. This article explores this idea. It does so primarily by reporting and discussing some findings from a study about British mothers' experiences of using formula milk for infant feeding. The paper begins by contextualising this discussion by briefly outlining some aspects of the construction of infant feeding as a social problem in Britain, focusing in particular on the influence of 'the new paradigm of health'.