Subjects fulfill DSM-IV criteria for Bipolar I disorder (BPI), Bipolar II disorder (BPII), Bipolar disorder not otherwise specified (BPNOS), or schizoaffective disorder bipolar type.

Subjects must be competent to comprehend the purpose of the study and provide informed consent.

Subjects must undergo complete psychiatric diagnostic interview (SCID--DSM-IV), medical, neurological, and Laboratory examinations (including EKG, renal and liver function tests, serum electrolytes, urinalysis, HIV, hepatitis B, pregnancy testing, and urine drug screen for the presence of psychoactive drugs and drugs of abuse).

At least 18 years old.

Subjects must have a depression of sufficient severity to rate greater than or equal to 16 on the Inventory of Depressive Symptomatology -Clinician (IDS-C) comparable to greater than or equal to 12 on the Hamilton Depression Rating Scale) or the clinician must decide that there is a need to treat with an antidepressant. In addition, patients must be on at least one mood stabilizer.

Subjects should have no general medical illness that is causing the mood disorder.

Subjects should not have liver, renal, hematological, or neurological disease.

Women participants of childbearing potential must be nongravid, nonnursing, and using an acceptable method of birth control.

Patients must not have alcohol or substance use or dependence of sufficient magnitude to require independent, concurrent treatment intervention (excluding self-help groups), i.e., hospitalization, day treatment programs, or counselor visits.

No patients taking concomitant medications that would contraindicate the medications under study, such as chemotherapy.

No history of bulimia or seizure disorder.