SWitching to Abilify Trial (SWAT)

Inclusion Criteria: Signed written informed consent Men and women, ages 18 to 65. Women of childbearing potential (WOCBP) must be using an adequate method of contraception to avoid pregnancy throughout the study in such a manner that the risk of pregnancy is minimized. Patients who have not been hospitalized during last three months Patients who have kept clinically stable dosage during last one month Patients with a diagnosis of schizophrenia and schizoaffective disorder as defined by DSM-IV criteria Patients whose symptoms are not optimally controlled or whose antipsychotic medication is not well-tolerated, which in the clinical judgment of the treating psychiatrist require a change of treatment. Patients who have received antipsychotics in the past must have shown a response to a neuroleptic medication other than clozapine. Exclusion Criteria: Patients who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period Women who are pregnant or breastfeeding Patients who are at risk for committing suicide: either having active suicidal ideation considered clinically significant or recently attempted suicide Patients with a diagnosis of bipolar disorder, depression with psychotic symptoms, or organic brain syndromes Patients who have met DSM-IV criteria for any significant Psychoactive Substance Use Disorder within the 3 months prior to Screening Patients considered treatment-resistant to antipsychotic medication (patients need to have shown a previous response to a antipsychotic medication other than clozapine) and patients with a significant history of intolerance to multiple antipsychotic treatments Treatment with a long-acting antipsychotic (i.e., haloperidol decanoate or fluphenazine decanoate) in which the last dose was within 3 weeks of randomization. Patients with a history of neuroleptic malignant syndrome Patients with epilepsy, a history of seizures (except for a single childhood febrile seizure), or a history of an abnormal EEG, severe head trauma, or stroke or who have a history or evidence of other medical conditions (e.g., congestive heart failure) that would expose them to an undue risk of a significant adverse event or interfere with assessments of safety or efficacy during the course of the trial Patients who would be likely to require prohibited concomitant therapy during the trial Patients who have previously enrolled in an aripiprazole clinical study or who have participated in any clinical trial with an investigational agent within the past month Prisoners or subjects who are compulsorily detained for treatment of either a psychiatric or physical (e.g., infectious disease) illness must not be enrolled into this study.