Time of relapse=date when patient meets relapse criteria. There are 4 definitions for relapse: 1. Patient meets the following criteria for 2 consecutive visits: (a) Aberrant Behavior Checklist Irritability score ≥25% than score at end of Phase 1 AND (b) Clinical Global Impression Improvement scale rating of 'Much Worse' or 'Very Much Worse' relative to rating at end of Phase 1. If relapse criteria met at 1 visit, 2nd visit should occur in about 1 week to reevaluate whether relapse criteria are still met. 2. Patient discontinues for "Lost to Follow-up" after a visit in which he or she met Definition 1 criteria (a&b). 3. Patient begins a prohibited drug (whether a study investigator or outside source prescribed) to treat worsening symptoms of irritability of autistic disorder after a visit where patient met Definition 1 criteria (a&b). 4. Patient discontinues due to hospitalization for worsening symptoms of irritability or due to lack of efficacy based on investigator's assessment.

All participants who were randomized in Phase 2

ABC is an informant-based checklist used to assess and classify problem behaviors of children and adolescents with mental retardation. The 58 items are rated on a 4-point scale (0=not at all a problem to 3=the problem is severe in degree), and resolve into 5 subscales: 1) irritability, agitation; 2) lethargy, social withdrawal; 3) stereotypic behavior; 4) hyperactivity, noncompliance; and 5) inappropriate speech. The ABC can be completed by parents, special educators, psychologists, direct caregivers, nurses, and others knowing the participant. Psychometric assessment of the ABC indicates that its subscales have high internal consistency, adequate reliability, and established validity. The ABC-I Subscale Score ranges from 0 to 45, with a negative change in score signifying improvement. LOCF data set includes data recorded at a given visit or, if no observation was recorded at that visit, data carried forward from the prior visit. chg=change; BL=baseline; APR=aripiprazole; vs=versus.

All participants who were randomized and took at least 1 dose of double-blind medication in Phase 2 and who had at least 1 efficacy evaluation after the start of Phase 2 study drug.

CG-I rating scale permits global evaluation of patient's improvement over time. At baseline (BL), CGI Severity of Illness assessment is performed, in which the clinician rates severity of patient's condition on a 7-point scale ranging from 1=no symptoms to 7=very severe symptoms. Higher total score=worse symptoms. At subsequent visits, clinician assesses patient's improvement relative to symptoms at baseline on CGI-I 7-point scale ranging from 1=very much improved to 7=very much worse. Since the drug targets irritability symptoms, the CGI focuses on severity of irritability secondary to autistic disorder. Lower score=more improved symptoms. LOCF data set includes data recorded at a given visit or, if nothing recorded, data areccarried forward from the prior visit. For secondary endpoints (endpt), hierarchical testing was used to keep overall experiment-wise type I error rate to <=0.05. diff=difference; IS=irritability scale; PA=primary analysis; signif=significance/significantly.

All participants who were randomized and took at least 1 dose of double-blind medication in Phase 2 and who had at least 1 efficacy evaluation after the start of Phase 2 study drug.

AE=any new unfavorable symptom, sign, or disease or worsening of a preexisting condition that may not have a causal relationship with treatment. SAE=a medical event that at any dose results in death, persistent or significant disability/incapacity, or drug dependency/abuse; is life-threatening, an important medical event, or a congenital anomaly/birth defect; or requires or prolongs hospitalization.

All participants who took at least 1 dose of single-blind aripiprazole in Phase 1

AE=any new unfavorable symptom, sign, or disease or worsening of a preexisting condition that may not have a causal relationship with treatment. SAE=a medical event that at any dose results in death, persistent or significant disability/incapacity, or drug dependency/abuse; is life-threatening, an important medical event, or a congenital anomaly/birth defect; or requires or prolongs hospitalization. Treatment-related=having certain, probable, possible, or missing relationship to study drug.

All participants who were randomized and took at least 1 dose of double-blind medication in Phase 2