The ADOS-2 is a standardised assessment of communication, social interaction and imaginative use of materials conducted with the child being assessed. It lasts about 1 hour. The ADOS-2 consists of standard activities that allow the examiner to observe behaviours that have been identified as important to the diagnosis of Autism Spectrum Disorders at different developmental levels and chronological ages. It involves a number of tasks and conversational items that are different according to the level of expressed language, and are designed to elicit social interaction and understanding. The ADOS-2 is an internationally recognised tool to assist the clinical assessment and contributes both observations and quantifiable results via the diagnostic algorithm and the comparison score.