A preregistered experimental study tested the effects of message framing on breastfeeding and formula-feeding attitudes and intentions. It also examined whether affective reaction and information acceptance mediated these effects, and whether self-efficacy and perceived behavioral control (PBC) moderated them. Participants (282 pregnant women) were randomly assigned to a gain frame condition (benefits of breastfeeding), a loss frame condition (risks of not breastfeeding), or a control condition.