Bipolar disorder is a chronic and often devastating illness that may go undiagnosed because of its complex and diverse presentation. Clinicians can provide psychological treatments, in conjunction with pharmacotherapy, that can reduce the frequency, severity, and duration of manic and depressive episodes. Because bipolar disorder is characterized by high degrees of comorbidity and high rates of medical complications, the clinician will frequently need to implement other treatments targeted to comorbid conditions, such as panic, generalized anxiety, substance abuse, and personality disorders. This article introduces the issue of Journal of Clinical Psychology: In Session devoted to the treatment of bipolar disorder. We describe the cognitive styles and personal vulnerabilities that pose greater risk for bipolar disorder. Three evidence-based psychological treatments (interpersonal social rhythm therapy, family-focused treatment, and cognitive-behavioral therapy) and current pharmacological treatments are examined and illustrated. Finally, we review the effectiveness and practice implications of a variety of treatments for this severe and underresearched disorder.