Study of Aripiprazole in the Treatment of Children and Adolescents With Autistic Disorder (AD)

Inclusion Criteria: * Meets current Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnostic criteria for AD and demonstrates serious behavioral problems; diagnosis confirmed by Autism, Diagnostic Interview-Revised (ADI-R). * CGI score \> = 4 AND an ABC Irritability/Agitation subscale score \> = 18 at screening and baseline (randomization) * Mental age of at least 18 months * Male or female 6 to 17 years of age inclusive, at the time of randomization Exclusion Criteria: * Patients considered treatment resistant to neuroleptic medication based on lack of therapeutic response to 2 different neuroleptics after treatment of at least 3 weeks each * Patients previously treated and not responding to aripiprazole treatment * The patient is currently diagnosed with another disorder on the autism spectrum, including PDD-NOS, Asperger's Disorder, Rett's Disorder, Fragile-X Syndrome or Childhood Disintegrative Disorder * Current diagnosis of bipolar disorder, psychosis, schizophrenia, or major depression * A seizure in the past year * History of severe head trauma or stroke * Non-pharmacologic therapy (e.g., psychotherapy, behavior modification) should be stable prior to screening and consistent throughout the study