Women are particularly vulnerable in the peripartum period for either developing a mental illness or suffering symptom exacerbation. These illnesses are often experienced covertly, however, and women may not seek out professional help, even though their symptoms may be seriously affecting their well-being and parenting. This article provides an overview of mental illnesses that can present in the peripartum period, with the aim of improving their early detection, diagnosis, and treatment by health professionals. The authors examine the risks that peripartum mental illness may pose to parenting and explore reasons why many women keep their illness secret.