Underlying persistent psychological difficulties have been found to moderate potential adverse effects of maternal postpartum depression (PPD) on parenting and infant development. The authors examined whether mothers presenting postpartum depressive symptoms showed higher levels of personality pathology and more insecure state of mind regarding attachment compared to nondepressed mothers. Participants (N = 85) were assessed with the Edinburgh Postnatal Depression Scale (EPDS), the Present State Examination, the Adult Attachment Interview, and the Structured Clinical Interview for DSM-IV Axis II. Mothers with high EPDS scores were more likely to have a preoccupied insecure state of mind and to have personality disorder compared with mothers scoring below clinical cutoff. Furthermore, multiple regression analysis showed that personality disorder and AAI classification were independently related to EPDS score, and that these two factors together accounted for 48% of the variance in EPDS score. Findings are discussed in terms of heterogeneity in PPD populations and underline the importance of examining potential coexisting psychological difficulties when studying PPD.