The historical antecedents of the current diagnostic criteria for mania involve the German phenomenologic descriptions of the late 1800s, the introduction of lithium for treatment and prevention of mania (which broadened the definition of mania in this country), the attempts to subclassify bipolar disorder into at least two subtypes, and the differentiation of patients with mania and hypomania from those with depression alone. Current diagnostic criteria for bipolar disorder are delineated in DSM-III-R. The differential diagnosis of bipolar disorder includes other conditions that may have manic-like symptoms, including organic mood disorders such as endocrine or metabolic conditions, drug intoxications, and tumors. Mania occurring in the context of substance abuse would be called a secondary mania. In addition, schizoaffective disorder can be diagnosed if there is a manic syndrome superimposed in the context of schizophrenia. Because of the absence of duration criteria for mania in DSM-III-R, the differential diagnosis within the bipolar disorders is largely based on severity and duration of depression. A problem in studying mania at present is that the prototypic cases have largely disappeared from treatment centers because of the success of lithium maintenance treatment. Patients available for study at psychiatric treatment facilities are largely treatment resistant, atypical, and likely to have experienced considerable amounts of substance abuse in their histories. Among the changes being considered for DSM-IV are to include duration criteria for mania, to separate bipolar II patients (depression and hypomania) from bipolar not otherwise specified, to refine the criteria for hypomania, and to add rapid cycling to the list of parenthetical modifiers for bipolar disorder with mania and bipolar disorder with hypomania.