Previous studies show that maternal mind-mindedness positively impacts children’s social development. In the current studies, we examine the relation between mind-mindedness during parent–child interaction, oxytocin (OT), and postnatal depression in a sample of mothers (N = 62, ages 23–44) and their infant (ages 3–9 months). In Study 1, infant salivary OT was positively correlated with mothers’ appropriate mind-related comments, and negatively correlated (at trend level) with maternal depression scores. Mothers experiencing symptoms of depression used fewer appropriate mind-related comments than controls. Study 2 was a double-blind, placebo-controlled, experimental study, in which the same women who participated in Study 1 were administered nasal OT. This did not significantly influence levels of mind-mindedness. Study 2 warrants a larger trial to investigate the effect of OT on mind-mindedness further. Study 1 is the first to demonstrate an association between maternal mind-mindedness and variation in children’s OT levels. Since both OT and mind-mindedness have been repeatedly implicated in processes of maternal–infant attachment, this association highlights the centrality of mothers’ caregiving representations in facilitating the parent–child relationship and children’s early development.