A cohort of adolescent (ages 13-18) patients with bipolar disorder and current manic symptoms will be approached for participation in this 3-month outpatient study. Taurine or matching placebo will be administered orally, in capsules, and added to whatever medication(s) the patients are receiving from their clinicians. The specific medications and dosages will be determined solely by the subjects' non-study clinicians ("treatment-as-usual"). During the 3 months of the study, subjects will be required to keep their medications nearly constant (minor dosage adjustments for side-effects or to maintain therapeutic levels will be permitted) for the duration of the trial. Since taurine will be an adjunctive therapy, patients currently taking mood stabilizers can continue to do so. The research team will work closely with the subject and their outpatient clinician(s) to coordinate the medication issues. The results from standard rating scales for bipolar disorder research will be compared between the group receiving the taurine and the group receiving placebo.