The Autism Diagnostic Observation Schedule (ADOS) is a semi-structured, standardized assessment tool used for diagnosing Autism Spectrum Disorders (ASDs). The study reviewed the item and domain total distributions of ADOS Modules 1–3 in 1,630 assessments of children aged 14 months to 16 years with ASD or heterogeneous non-spectrum disorders. The revised algorithm includes two new domains, Social Affect and Restricted, Repetitive Behaviors (RRB), combined into a single score with applied thresholds, aiming to improve predictive value. The research addresses concerns about floor and ceiling effects, the impact of impairment level, and the inclusion of RRB items. The goal is to enhance the sensitivity and specificity of the ADOS algorithms, making them more effective in diagnosing ASDs and distinguishing between different disorders.The Autism Diagnostic Observation Schedule (ADOS) is a semi-structured, standardized assessment tool used for diagnosing Autism Spectrum Disorders (ASDs). The study reviewed the item and domain total distributions of ADOS Modules 1–3 in 1,630 assessments of children aged 14 months to 16 years with ASD or heterogeneous non-spectrum disorders. The revised algorithm includes two new domains, Social Affect and Restricted, Repetitive Behaviors (RRB), combined into a single score with applied thresholds, aiming to improve predictive value. The research addresses concerns about floor and ceiling effects, the impact of impairment level, and the inclusion of RRB items. The goal is to enhance the sensitivity and specificity of the ADOS algorithms, making them more effective in diagnosing ASDs and distinguishing between different disorders.