Bipolar disorders encompass a spectrum of mental illnesses that exhibit a chronic course and can lead to significant psychosocial stress. Many affected individuals receive their diagnosis too late and go for many years without specific treatment. An important reason for this is the overlap of clinical symptoms with those of other mental disorders. According to current understanding, a substantial proportion of seemingly unipolar recurrent depressive disorders likely belongs to the bipolar spectrum. There are also overlaps with symptoms from schizophrenia spectrum disorders, ADHD, and personality disorders. In recent years, there has been a paradigm shift in the understanding of the nature of bipolar disorders. This textbook addresses all the facts related to the diagnosis and treatment of bipolar disorders.