This chapter, written for undergraduate medical students and post-graduate doctors in training, presents information on how to manage low mood — a case which they are likely to encounter in the future in a general practice setting. It presents the case of a 21-year-old woman who has just given birth. She seems very tired and quiet and the GP notices that she does not seem overly enthusiastic about her baby who is asleep. She has not been interested in anything and not at all interested in sex, although she did have a large episiotomy and so she is still sore. The chapter provides details of the patients' medical history and the key findings of clinical examination, together with initial investigation results data for evaluation, and helps them develop their skills of clinical reasoning. Key questions then prompt the student to evaluate the patient, and reach a decision regarding their condition and the possible treatment plan.