Paliperidone palmitate is being developed as a long-acting intramuscular injectable formulation for the treatment of schizophrenia. Many patients with schizophrenia achieve symptom stability with the available oral antipsychotic medications; however, it is estimated that up to 75% have difficulty adhering to a daily oral treatment regimen. Long-acting injectable formulations may make compliance with the treatment regimen easier by eliminating the need for daily medication. An injectable formulation of risperidone is widely used in the treatment of schizophrenia and has been well tolerated by patients with chronic schizophrenia at the recommended dosage of 25 to 50 milligrams every 2 weeks. The present study is designed to evaluate the comparability of paliperidone palmitate and long-acting injectable risperidone over 1 year of treatment.