Autism spectrum disorders (ASDs) are neurodevelopmental disorders whose core features of impaired social communication and atypical repetitive behaviors and/or restrictions in range of interests emerge in toddlerhood and carry significant implications at successive stages of development. The ability to reliably identify most cases of the condition far earlier than the average age of diagnosis presents a novel opportunity for early intervention, but the availability of such an intervention is disparate across US communities, and its impact is imperfectly understood. New research may transform the clinical approach to these conditions in early childhood.