The Autism Diagnostic Interview-Revised (ADI-R) is a structured interview conducted with the parents of individuals who have been referred for the evaluation of possible autism or autism spectrum disorders. The interview, used by researchers and clinicians for decades, can be used for diagnostic purposes for anyone with a mental age of at least 24 months and measures behavior in the areas of reciprocal social interaction, communication and language, and patterns of behavior. Structure Useful for diagnosing autism, planning treatment, and distinguishing autism from other developmental disorders. The interview covers the referred individual's full developmental history, is usually conducted in an office, home or other quiet setting by a psychologist, and generally takes one to two hours. The caregivers are asked 93 questions, spanning the three main behavioral areas, about either the individual's current behavior or behavior at a certain point in time. The interview is divided into five sections: opening questions, communication questions, social development and play questions, repetitive and restricted behavior questions, and questions about general behavior problems. Because the ADI-R is an investigator-based interview, the questions are very open-ended and the investigator is able to obtain all of the information required to determine a valid rating for each behavior. For this reason, parents and caretakers usually feel very comfortable when taking part in this interview because what they have to say about their children is valued by the interviewer. Also, taking part in this interview helps parents obtain a better understanding of autism spectrum disorder and the factors that lead to a diagnosis. Content areas The first section of the interview is used to assess the quality of social interaction and includes questions about emotional sharing, offering and seeking comfort, social smiling, and responding to other children. The communication and language behavioral section investigates stereotyped utterances, pronoun reversal, and social usage of language. Stereotyped utterances are the few words or sounds that the individual uses and repeats most often. The restricted and repetitive behaviors section includes questions about unusual preoccupations, hand and finger mannerisms, and unusual sensory interests. Finally, the assessment contains questions about behaviors such as self-injury, aggression, and over activity which would help in developing treatment plans. Scoring After the interview is completed, the interviewer determines a rating score for each question based on their evaluation of the caregiver's response. Rating scale 0: "Behavior of the type specified in the coding is not present" 1: "Behavior