About 84% of children diagnosed with autism spectrum disorder (ASD) between ages 12 months to 36 months retained the diagnosis on subsequent evaluations. Of 400 young children who were diagnosed with ASD before age three, 336 retained that diagnosis on a subsequent evaluation. Within the very youngest age bands, the stability of an ASD diagnosis was highest at 16 months at 0.83. Across all age bands, however, stability was extremely high by 30 months at 0.97. Toddlers age 14- to 16-months old identified as having ASD have a low chance of testing within typical development levels at . . .