A Study to Evaluate the Efficacy and Safety of Adjustable Doses of Extended-release (ER) Paliperidone Compared With Placebo, in Combination With Lithium or Valproate, to Treat Manic and Mixed Episodes in Patients With Bipolar I Disorder

Inclusion Criteria: * Meets Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition (DSM-IV) criteria for Bipolar I Disorder, Most Recent Episode Manic or Mixed (with or without psychotic features) * History of at least 1 previously documented manic or mixed episode requiring medical treatment within the past 3 years * Must have been taking lithium or valproate as part of treatment for Bipolar I Disorder for at least 2 weeks before screening, with drug levels at screening within therapeutic range * Total YMRS score of at least 20 at screening and at baseline (Day 1) * Women must be postmenopausal for at least 2 years or agree to practice an effective method of birth control throughout the study. Exclusion Criteria: * Meets DSM-IV criteria for rapid cycling and schizoaffective disorder * In the opinion of the study doctor, is at significant risk for suicidal or violent behavior during the course of the study * Has used cocaine, phencyclidine, amphetamine, methylphenidate, pemoline, an opioid (excluding codeine), hallucinogen, or any other drug that may be associated with manic symptoms as evidenced by a positive urine drug screen * Has received benzodiazepines at doses equal to 4 mg/day of lorazepam or higher for a period of 3 months or longer immediately before the screening phase.