Interpersonal psychotherapy (IPT) is an empirically validated treatment for mood disorders, anxiety disorders, eating disorders, and trauma. IPT is based on the concept of “relational frame”—that an individual's experience of psychological distress impacts those around them, and that their social support network impacts the distressed individual. This concept, along with the specific techniques and tools that flow from it and the theoretical bases of IPT (attachment and interpersonal theory) make IPT unique. In this article we review the theoretical bases of IPT (attachment and communication) and provide a brief history of IPT, as well as the evidence supporting its use for a variety of disorders. We also describe its application to groups, adolescents, and other diverse populations. Future directions for research and treatment development are proposed, particularly research in the area of combining IPT with other psychotherapeutic modalities.