Course of illness is central to our focus on bipolar disorder due to the lifelong nature of this illness in the majority of patients. In this overview, we highlight areas of consensus and debate on factors that impact course of illness. Findings on age at onset, psychiatric comorbidity, frequency of episodes, cycle pattern, rapid cycling, mixed symptoms, and precipitants of episodes including use of substances and antidepressants and lithium discontinuation are discussed. The diversity and range of presentation and even course of illness become quickly apparent in this review. Highlighting these factors rather than seeking a unifying theory should be a productive way to refine our ability to identify additive factors contributing to course of illness for patients with bipolar disorder.