The notion that maternal reflective functioning, namely the mother's capacity to hold her baby and his mental states in mind, plays a vital role in the intergenerational transmission of attachment is investigated (Fonagy, Gergely, Jurist, & Target, 2002; Fonagy et al., 1995; Slade, this volume). A parent's capacity to understand the nature and function of her own as well as her child's mental states, thus allowing her to create both a physical and psychological experience of comfort and safety for her child, is proposed. In this study of 40 mothers and their babies, maternal reflective functioning is measured using the Parent Development Interview (PDI; Aber, Slade, Berger, Bresgi, & Kaplan, 1985), and scored for reflective functioning using an addendum to Fonagy, Target, Steele, & Steele's (1998) reflective functioning scoring manual (Slade, Bernbach, Grienenberger, Levy, & Locker, 2004). The relations between maternal reflective functioning and both adult (measured in pregnancy) and infant attachment (measured at 14 months) are examined. The findings indicate that relations between adult attachment and parental reflective functioning are significant, as are relations between parental reflective functioning and infant attachment. A preliminary mediation analysis suggests that parental reflective functioning plays a crucial role in the intergenerational transmission of attachment.