The immediate postpartum period is a time of acute vulnerability to mental illness, which presents unique challenges for the psychiatric consultant. Because the postpartum hospital stay is typically brief, the consultant must have a working knowledge of postpartum physiology and the myriad forms of mental illness that may emerge in this vulnerable time, in order to quickly make a diagnosis and formulate a treatment plan. This review aims to characterize the most common reasons for postpartum consultation, review postpartum physiology and psychiatric conditions, and propose an evidence-based, practical approach to treatment. A literature search using the terms "postpartum," "obstetric," "consultation," and "psychiatry" yielded six studies that identified reasons for psychiatric consultation to the obstetrics and gynecology services. These studies informed the structure of the article such that we review the most common reasons for consultation and how to approach each issue. The most common reason for consultation is past psychiatric history, often in the absence of current symptoms. For each clinical situation, including depression, adverse birth events, and psychosis, we present a differential diagnosis, as well as risk factors, clinical signs, and recommended treatment.