Cognitive theories of depression maintain that negative thoughts about the self and of the future are central features of depression. In postnatal depression, these negative thoughts may impact upon the mother's experience of parenting. This study investigated the impact of maternal depression during the first postnatal year and beyond and infant gender on parenting stress, on the mother's feelings of attachment to her infant and on her perceptions of her infant's behaviour. One hundred and twelve generally well-educated middle-class mothers who had presented with unsettled infant behaviour to a parent-craft hospital, were interviewed and completed questionnaires when their infants were 4, 12 and 15 months of age. Mothers who had experienced depression reported higher levels of parenting stress at 15 months than never depressed mothers. Only mothers who had experienced chronic depression (12 months duration), however, reported higher parenting stress related to characteristics of their infants. They also reported significantly more negative perceptions of their infant's behaviour and more hostile feelings towards their infants than never depressed mothers. Results are discussed with respect to the impact of the duration of depression on the mothers' reported experiences of parenting and the clinical implications of these findings.