Unlike bipolar I disorder (BD I), which has been extensively studied and depicted in popular literature and on screen, bipolar II disorder (BD II) is poorly understood, underdiagnosed, and insufficiently treated. This has often resulted in an over 10-year delay in diagnosis. BD II is mistakenly described a “lesser form” of BD I, despite numerous studies showing comparable illness severity and risk of suicide in these two BD subtypes. Perhaps because of its under-recognition, treatment studies of BD II are limited, and too often results from studies of patients with BD I are simply applied to those with BD II with no direct evidence supporting this practice. BD II is an understudied and unmet treatment challenge in psychiatry. This talk will provide a broad overview of BD II including differential diagnosis, course of illness, suicide risk and evidence-based treatment options.