Bipolar disorder is a recurrent and sometimes chronic illness involving episodes of depression and mania or hypomania. The most frequent presentation is depression: more than 1 of 5 primary care patients with depression have bipolar disorder. The symptoms of bipolar depression often differ from those of unipolar depression. Age of onset for bipolar disorder is usually the late teens; slightly older for bipolar II subtype. Nearly all patients with bipolar disorder suffer from a comorbid psychiatric disorder, most frequently an anxiety disorder. Although the most dramatic presentation of bipolar disorder is the acutely manic patient who presents to the emergency department, this presentation is much less frequently encountered in physicians' offices, both primary care and psychiatric. Bipolarity is often missed in these situations. About half of bipolar patients have consulted 3 or more professionals before receiving a correct diagnosis, and the average time to first treatment is 10 years. It is imperative that clinicians carefully assess patients for bipolar disorder, especially those presenting with depression. In addition to patient and family history, administration of a screening instrument can be very helpful. The most widely used screening tool is the Mood Disorder Questionnaire. This screening tool will be discussed in this article regarding its use in outpatient clinics and the community.