Bipolar disorder is a psychiatric disorder that is episodic and chronic and can lead to significant impairment in a person’s life. The term bipolar disorders encompasses a number of diagnoses including bipolar I disorder, bipolar II disorder, cyclothymic disorder, substance/medication-induced bipolar and related disorder, bipolar and related disorder due to another medical condition, other specified bipolar and related disorder, and unspecified bipolar and related disorder as classified by the Diagnostic and Statistical Manual of Mental Disorders—5th edition (DSM-5). Late-life bipolar disorders generally refer to the onset of disorder in patients older than 60 years, though the cutoff age can be variable. The following chapter outlines an overview of the various bipolar disorders including the diagnosis, assessment, and evidence-based treatment of the bipolar disorders. The construct of «mixed mood episode» has also garnered much attention in recent years, with research in the area affecting views on management. This chapter also contains two case studies which demonstrate the diagnostic and management challenges one may encounter in an older adult with bipolar disorder. The interplay of systemic medical complexities in this population with various mood symptoms certainly increases the challenge of treating bipolar disorder.