The Autism Diagnostic Observation Schedule (ADOS) is a standardized diagnostic test for diagnosing and assessing autism, now in its second edition as of 2012. It is considered to be a "gold standard" in diagnosing Autism Spectrum Disorder (ASD). The protocol consists of a series of structured and semi-structured tasks, that involve social interaction between the examiner and the person under assessment. The examiner observes and identifies segments of the subject's behavior, and assigns these to predetermined observational categories. Categorized observations are subsequently combined to produce quantitative scores for analysis. Research-determined cut-offs identify the potential diagnosis of autism spectrum disorder, allowing a standardized assessment of autistic symptoms. The Autism Diagnostic Interview-Revised (ADI-R), a companion instrument, is a structured interview conducted with the parents of the referred individual, and covers the subject's full developmental history. The ADI-R has lower sensitivity but similar specificity to the ADOS. History The Autism Diagnostic Observation Schedule was created by Catherine Lord, Michael Rutter, Pamela C. DiLavore and Susan Risi in 1989. It became commercially available in 2001 through WPS (Western Psychological Services). Method The ADOS consists of a series of structured and semi-structured tasks, and generally takes from 30 to 60 minutes to administer. During this time, the examiner provides a series of opportunities for the subject to show social and communication behaviors relevant to the diagnosis of autism. Each subject is administered activities from just one of five modules (T, 1, 2, 3, 4). The selection of an appropriate module is based on the developmental and language level of the patient. The only developmental level not served by the ADOS is that for adolescents and adults who are nonverbal. The ADOS should not be used for formal diagnosis with individuals who are blind, deaf, or otherwise seriously impaired by sensory or motor disorders, such as cerebral palsy or muscular dystrophy. Modules Module 1 is used with children who use little or no phrase speech. Subjects who do use phrase speech, but do not speak fluently, are administered Module 2. Since these modules both require the subject to move around the room, the ability to walk is generally taken as a minimum developmental requirement to use of the instrument as a whole. Module 3 is for children/adolescents who are verbally fluent, and Module 4 is used with older adolescents and adults who are verbally fluent. Some examples of Modules 1 or 2 include response to name,