— During the last three decades, we have witnessed dramatic improvements in both the psychosocial and pharmacological treatments of affective disorders. Administered in concert with the new medications advances in pharmacology have produced, disorder-specific psychosocial treatments have further improved the prognosis and course of bipolar and unipolar disorder. Methods — We review our research on unipolar and bipolar disorder and their treatment, in particular interpersonal psychotherapy (IPT) and modifications thereof. Results — We provide empirical evidence that IPT is an efficacious acute and maintenance treatment for affective disorders. Our cumulative research and clinical experience suggest that interpersonal relations and circadian and social rhythms influence affective illnesses and that psychotherapy may aid in normalizing problems in these areas for patients with affective illnesses. Conclusions — Despite the excitement generated by the recent progress in research on mental disorders and their treatment, we are yet to fulfill the promise that the explosion of knowledge about targeted pharmacotherapies or psychotherapies would seem to offer. To move our field forward, we must continue to apply scientific rigor and thought to understanding the suitability of current nomenclatures, the impact of comorbid psychiatric and medical illnesses and symptoms on the manifestation and treatment of affective disorders, and the practicality of widespread utilization of new treatments.