The proposed study is a randomised clinical trial comparing cognitive behaviour therapy with routine clinical care for pregnant, depressed women. The study will evaluate the effectiveness of cognitive behaviour therapy and routine clinical care in the treatment of antepartum depression, and the prevention of postpartum depression. The impact of depression, and recovery from depression, on mother-infant interaction will also be evaluated. Pregnant women attending routine ultrasound scan at 18 weeks gestation will be screened for depressive symptoms. Selected women will then be assessed in order to recruit a sample of depressed women (N=240). Depressed, consenting women will then be randomised to either cognitive behaviour therapy (N=120) or routine clinical care (N=120). All participants will be evaluated at 36 weeks gestation (following treatment) and six months postpartum. Outcome measures will include measures of maternal mental health, mother-infant interaction, adjustment and functioning. The proposed study addresses issues of important clinical relevance, for which the current literature provides little guide.