Given the high risk of postpartum psychiatric problems, clinicians need to be prepared to appropriately manage the breast-feeding woman who needs psychotropics. These psychiatric researchers examine the issues and offer guidelines. Following childbirth, many women are at high risk for the onset or recurrence of psychiatric illness. Women who need psychopharmacologic treatment may wish to breast-feed their infants, but the data regarding the degree of drug passage to the infant and the subsequent effects of this exposure on infant growth and development are very limited, leaving clinicians with little guidance for responding in ways that protect the health and well-being of both mother and infant. In general, the less protein-bound, the more lipid-soluble, and the more weakly basic a drug is, the more likely it is to diffuse into breast milk. When a psychotropic medication is administered, the infant's clinical status and serum concentrations, including metabolite concentrations, should be closely monitored. Among the agents that have been the subject of at least limited studies in breast-feeding women are tricyclic antidepressants, selective serotonin reuptake inhibitors, benzodiazepines, and the mood stabilizers lithium, carbamazepine, and divalproex. This article examines the factors that influence infant exposure to psychotropic medication through breast-feeding and includes clinical guidelines for managing the breast-feeding woman on psychotropics as well as protecting and caring for her infant.