The study aims to examine the skill of communication repair (i.e., the ability to respond effectively to a request for clarification of an unclear message) across three neurodevelopmental disabilities in which language skills are impaired. Participants include children aged 3 to 15 years with fragile X syndrome, Autism Spectrum Disorder, Down syndrome and controls with typical development. Participants were recruited from parent groups, childcare centres, schools, research registries, and clinics in the eastern, southeastern, and midwestern United States of America. Over 200 participants completed a baseline assessment. Participants are assessed annually up to three times.