The aim of this prospective study was to examine temporal pathways from mothers’ reflective functioning (RF) through parenting to infant attachment measured more than 16 months later. Participants were 88 mother–infant dyads from demographically diverse backgrounds and included a group of mothers with histories of childhood maltreatment. RF was assessed using the RF rating of the Adult Attachment Interview before the birth of the baby. Parenting was assessed when the infants were 6 months old using the Maternal Sensitivity scale, as well as when they were 16 months using the Disconnected and Extremely Insensitive Parenting scale. Infant attachment was assessed when the infants were 16 months old using the Strange Situation. As hypothesised, the study findings showed that mothers’ mentalization regarding their own early attachment relationships was associated with later parenting and infant attachment. Negative parenting behaviours explained the link between mothers’ RF about their own attachment relationships and infant attachment disorganization. The findings suggest that mothers’ mentalization about their early attachment relationships has important implications in the transition to becoming parents themselves. Mentalization appears to be particularly important in helping mothers screen and inhibit negative parenting behaviours that would otherwise undermine infant attachment security and organization.