Introduction – The diagnostic pathway for autism spectrum disorders (ASD) was the subject of recommendations by the French National Authority for Health (HAS) in 2018, but remains poorly documented in France. Using comprehensive data from a registry of children with disabilities in Isère and Savoie, this study aims to describe and evaluate the extent to which the diagnostic pathways for children and adolescents with autism align with these recommendations.Method – The registry data are primarily derived from the records of the departmental offices for people with disabilities (MDPH) and are supplemented by the Program for the Medicalization of Information Systems (PMSI) in child and adolescent psychiatry. Among 710 eligible families, 223 parents of children diagnosed with ASD before age 8 and 131 parents of adolescents diagnosed with ASD between ages 8 and 15 were interviewed by telephone to document the child’s entire diagnostic pathway from the first signs of symptoms to diagnosis.Results – Analysis of the diagnostic journey for these two subpopulations reveals differences in profiles between early and late diagnoses. The average ages at autism diagnosis were 5.4 years for children and 12.3 years for adolescents, 3.5 and 9.5 years, respectively, after the onset of the first signs. Autism is rarely suspected during the initial consultation or screening.Discussion – These results underscore the urgent need to improve training for frontline professionals in the screening for autism: healthcare professionals—general practitioners and pediatricians—as well as early childhood educators, school system staff, and paramedical professionals.