The Ritvo Autism Asperger Diagnostic Scale-R (RAADS_R) is a tool to diagnose Autistic Disorder (AD) in adolescence using a structured clinical interview and an adjunct to diagnosis. This 80-item scale has been validated in an international multicenter study (Sensitivity = 97%, Specificity = 100%, Accuracy =98%). During the Workshop, participants gain proficiency in diagnosing Autistic Disorder in adolescents for their clinical and research purposes. Each attendee fills out and scores the scale, and each question is discussed in terms of the symptom category it assesses. Also, this Workshop teaches a strategy for obtaining relevant diagnostic information from adolescents and family members. Attendees also share experiences and discuss problems they have had in diagnosing Autism Spectrum Disorder.