Bipolar disorders are a group of psychiatric disorders that are episodic and chronic and can lead to significant impairment. The term bipolar disorders encompasses a number of illnesses 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, unspecified bipolar and related disorder, and unspecified mood disorder as classified by the Diagnostic and Statistical Manual of Mental Disorders—5th edition, text revision (DSM-5-TR). Late-onset bipolar disorders generally refer to the onset of disorder in patients older than 60 years, though the cutoff age can be variable. Late-life bipolar disorder includes both aging patients whose disorder presented earlier in life and patients whose disorder presents for the first time in later life. This 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.