Based on the analysis of cognitive style, this study demonstrated that women experiencing postnatal depression (PND) fall into two categories: (a) those with a general cognitive vulnerability to depression and for whom childbirth is a non-specific stressor; and, (b) those whose depression is directly related to the stressful demands of motherhood. Studying an Australian sample of 406 postnatal women who completed the Edinburgh Postnatal Depression Scale (EPDS), the Dysfunctional Attitudes Scale (DAS-24), and the Maternal Attitudes Questionnaire (MAQ), hierarchical cluster analysis identified three groups distinguished on the basis of depressive symptomatology and/or the nature and strength of maladaptive cognitions.