There are several diagnostic tools employed by professionals to diagnose Autism. These tools may be area specific (speech, cognitive development etc.) or comprehensive tools encompassing multiple areas of concern. These tools rely on two sources of information, Parents description of their child’s behaviour/issues and the professionals direct observation of the child during the assessment. Some examples of diagnostic tools are :

1. Childhood Autism Rating Scale (CARS) : Suitable for any child over 2 years of age, CARS is made up of  components of five important systems for diagnosing autism, each component covering an important area of development.
2. Autism Diagnosis Interview -Revised (ADI-R) : The ADI-R focuses on behavior in three main areas: reciprocal social interaction; communication and language; and restricted and repetitive, stereotyped interests and behaviors, it is designed for children and adults with mental ages about 18 months and above.
3. Diagnostic and Statistical Manual, 5th Edition (DSM-5): Prescribed by the American Psychiatric Association, DSM-5 provides standardized criteria to help diagnose ASD.
4. Indian Scale for Assessment of Autism (ISAA) : Based on CARS, ISAA was designed with the Indian Child in mind which covers the six domains, namely, social relationships and reciprocity; emotional responsiveness; speech, language and communication; behavior patterns; sensory aspects and cognitive component.