This is a multicenter, double blind (neither the patient nor the physician knows whether drug or placebo is being taken, or at what dosage), randomized (patients are assigned different treatments based on chance), placebo- and active-controlled, parallel-group study. Patients will be randomized into 1 of 3 treatment groups to receive oral dosages of Extended Release (ER) Osmotic Controlled-Release Oral Delivery System (OROS) paliperidone 6 mg, olanzapine 10 mg, or placebo. They will receive two capsules of Paliperidone ER 3 mg, placebo or Olanzapine 5 mg once daily after breakfast for 6 weeks. The study will include a screening period, followed by double-blind treatment for 6 weeks.