The purpose of the study is to evaluate the long-term safety profile of the Investigational Medication Depakote ER in the treatment of Bipolar I Disorder, manic or mixed episode, in children and adolescents ages 10-17.

Inclusion Criteria:

• Subject is between 10 and 17 years of age, inclusive, on Day 1 and weighs at least 60 lbs (27 kg).
• Subject has a current psychiatric diagnosis of bipolar I disorder, manic or mixed episode, based on the K-SAD-PL interview and DSM-IV-TR criteria.
• Subject is an outpatient in a manic or mixed episode with a YMRS score of greater than or equal to 16 during Screening and at Day 1.

Exclusion Criteria:

• Has an Axis I disorder other than Attention Deficit Hyperactivity Disorder (ADHD), Obsessive Compulsive Disorder (OCD), Oppositional Defiant Disorder (ODD), Conduct Disorder (CD), Panic Disorder, Enuresis, Encopresis, Parasomnias, Agoraphobia, Specific Phobia, Social Phobia or Separation Anxiety Disorder; or subject has an Axis II disorder that would interfere with the subject's ability to comply with study procedures or confound interpretation of the study results. Subject meets DSM-IV-TR criteria for substance abuse within the month prior to Screening, or meets the criteria for substance dependence within the three months prior to Screening, or exhibits signs of drug or alcohol intoxication or withdrawal at Day 1.
• Is expected to require hospitalization for the current manic or mixed episode.
• Is violent, homicidal, or suicidal such that, in the opinion of the investigator, the subject is at significant imminent risk of hurting self or others.
• Has a history of a chronic or acute medical disorder that, in the opinion of the investigator, would preclude compliance with the protocol, or confound interpretation of the study results.
• Has a history of, or is suspected of having a seizure disorder.
• Has any central nervous system (CNS) neoplasm, CNS infection, demyelinating disease, degenerative neurological disease, or any progressive CNS disease.
• Has Platelet count less than or equal to 100,000/µL
• Has blood chemistry ALT/AST value(s) greater than or equal to 2 times upper limit of normal at screening.
• Is taking a protocol allowed medication for ADHD that has not been stable for at least 3 months prior to Day 1, or that, in the investigator's opinion, may be exacerbating mood symptoms.
• Requires anticoagulant drug therapy.