A large group of infants of primiparous women who were at high risk fo r postnatal depression (N=188) and a smaller group of those at low risk (N=43) were assessed in the neonatal period using the Neonatal Behavioural Assessment Scale. Poor motor scores and high irritability were strongly predictive of the onset of maternal depression by eight weeks postpartum. These effects obtained after taking account of both maternal mood in the neonatal period and maternal perceptions of infant temperament. Poor motor scores and high levels of infant irritability in the neonatal period also predicted less optimal infant behaviour in face-to-face interactions with the mother at two months postpartum. Neonatal behaviour did not predict the persistence of depression, nor did it predict the quality of maternal behaviour in interaction with the infant.