Study Comparing Bifeprunox to Risperidone in Treatment of Outpatients With Schizophrenia With Weight as Primary Endpoint

Inclusion criteria: * Current treatment of at least 3 months with risperidone. * Primary diagnosis of schizophrenia. * Total Positive and Negative Symptoms Scale (PANSS) score \< or = 70 at screening and baseline. Exclusion criteria: * Psychiatric diagnosis other than schizophrenia as assessed by the modified Mini International Neuropsychiatric Interview (MINI) and considered by the investigator to be the primary psychiatric diagnosis. * History or presence of clinically significant cardiovascular, endocrine, hepatic, renal or other medical disease that might be detrimental to the subject or confound the study. * History of any suicide attempt within 3 years of day 1 or significant immediate risk of violence or suicidality.