Aberrant Behavior Checklist

The ABC is a 58-item caregiver-rated behavioral symptom checklist measuring irritability, social withdrawal, stereotypy, hyperactivity, and inappropriate speech. Used in ASD and intellectual disability clinical trials. Aman et al. (1985).

What is the Aberrant Behavior Checklist?

The Aberrant Behavior Checklist (ABC) is a validated 58-item caregiver-rated scale developed by Aman and colleagues (1985) to assess problem behaviors in individuals with intellectual disabilities. Originally validated in residential settings for adults with ID, the ABC has since been adapted as the ABC-Community (ABC-C) for outpatient and home settings, making it the most widely used behavioral outcome measure in autism spectrum disorder (ASD) clinical trials.

Each of the 58 items is rated on a 4-point scale (0 = not at all a problem, 1 = the behavior is a problem but slight in degree, 2 = the problem is moderately severe, 3 = the problem is severe in degree). Items are summed within each subscale, scores are not averaged.

The ABC Irritability subscale (ABC-I) is the primary endpoint in most aripiprazole and risperidone (both FDA-approved for ASD-related irritability in pharmacotherapy trials). A clinically meaningful response is typically defined as ≥25% reduction in ABC-I score from baseline.

ABC Subscale Score Interpreter

Enter your subscale scores to interpret severity. Scores are sums, not averages.

ABC copyright Michael Aman / Research Press. For clinical and research use. This interpreter does not replace clinical judgment.

ABC Subscale Reference

Aman et al. (1985). Subscale scores are raw sums. Clinically significant change in trials is typically defined as ≥25% reduction in the Irritability subscale (ABC-I) from baseline.

Common Clinical Trial Thresholds

Behavioral Outcome Tracking in HiBoop

ABC alongside CARS-2, Vineland, and adaptive behavior measures, integrated behavioral outcome monitoring for ASD, ID, and developmental disorder patient panels.