The objective of this study is to compare the safety and effectiveness of Risperidone, Olanzapine, and Quetiapine in the treatment of mania in children and adolescents with Bipolar disorder over 8 weeks and then over an extension phase. This is an exploratory, open-label study, which seeks to determine if there is evidence for efficacy. The results of this study will be used to generate hypotheses for a larger study.

Inclusion Criteria:

• Males and females age 6 to 18 years of age
• Patient must have a diagnosis of bipolar I or bipolar II disorder and currently displaying an acute manic, hypomanic, or mixed episode (with or without psychotic features) according to the DSM-IV based on clinical assessment and confirmed by structured diagnostic interview (Kidd Schedule of Affective Disorders).
• Patients must have an initial score on the Y-MRS total score of at least 15.
• Patient must be able to participate in mandatory blood draws.
• Patient must be able to swallow pills.

Exclusion Criteria:

• Patients with chronic medical illness, DSM-IV substance dependence within the past 6 months, pregnant or nursing females, and those at serious risk of suicide will be excluded from the study