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Helps diagnose autism and estimate the severity.

32607 Gilliam Autism Rating Scale- Third Edition, Kit (GARS-3 Kit)
32607B GARS-3 Instructional Objectives Manual
32607R GARS-3 Summary/Response Forms, Pk/50
32607M GARS-3 Examiner's Manual


Based on the 2013 diagnostic criteria for Autism Spectrum Disorder, as defined in the DSM-5.

James E. Gilliam

Age Range:  3 through 22 years
5-10 minutes

One of the most widely-used instruments for the assessment of Autism Spectrum Disorder (ASD), GARS-3 assists teachers, parents and clinicians in identifying Autism, and estimating its severity. It yields standard scores, percentile ranks, severity level, and probability of Autism.

GARS-3 consists of 56 clearly-stated items describing the characteristic behaviors of persons with Autism.  Items are grouped into six subscales:

  • Restrictive                                    
  • Social Interaction                                   
  • Social Communication
  • Emotional Responses           
  • Cognitive Style                                   
  • Maladaptive Speech

All six subscales have been empirically determined to be valid, and sensitive, for identification of individuals with ASD. Included in the GARS-3 are 44 new items, and a Diagnostic Validation Form to insure that test results meet the DSM-5 criteria for ASD. An Interpretation Guide, in the Manual, provides an easy and efficient method for assessing the probability and severity of the disorder.

All new validity studies show that the test results are valid for a wide variety of subgroups, as well as for the general population. Binary classification studies indicate that the GARS-3 is able to discriminate individuals with ASD from those without (i.e., sensitivity=.97, specificity=.97, ROC/AUC=.93). Confirmatory and exploratory factory analyses demonstrate the theoretical and empirical validity of the subscales.

Correlations of the GARS-3 scores with those of other well-known diagnostic tests for Autism are large, or very large, in magnitude. Test-retest (time sampling) reliability coefficients exceed .80 for subscales, and .90 for the Autism Indexes.  Interrater reliability intraclass coefficients exceed .80, and .84 for the Autism Indexes. Internal consistency (content sampling) reliability coefficients for the subscales exceed .85 and the Autism Indexes exceed .93.

The GARS-3 Kit includes 50 Summary/Response Booklets, the Instructional Objectives Manual and an Examiner’s Manual, in a storage box.