Project Summary Maximizing the benefits of early intervention for improving outcomes of individuals with neurodevelopmental disorders (NDD) such as autism spectrum disorder (ASD) requires widespread and efficacious early screening and identification practices. Despite decades of effort to identify early risk markers, there remain significant gaps in the identification-to-treatment pipeline. Prospective longitudinal studies of infant siblings of children with ASD have provided critical insights into the early symptoms, recurrence rate, and developmental trajectories of at-risk infants. However, the field remains limited by the near exclusive focus on infant siblings of children with ASD, despite similar patterns of familial inheritance within other neurodevelopmental and mental health disorders. One potential route to expanding the scope of early risk studies is the development of reliable and valid telehealth-based assessment tools. This would allow for prospective longitudinal investigation of infants living beyond the geographical bounds of University research sites as well as infants belonging to low incidence high-risk groups. There is supportive evidence for the efficacy of telehealth approaches for diagnostic evaluation and parent-mediated treatment for toddlers with ASD. Currently, there exist no valid and reliable tools for conducting behavioral assessments of infants' development via telehealth. This project directly compares a promising telehealth assessment tool, the TEDI, to gold-standard laboratory- based assessment tools. The TEDI utilizes a parent-coaching model to engage parents and infants in a specific set of semi-structured interactions from which standardized measures are scored and behavior ratings can be made. The proposed project has two aims, each of which focus on testing the reliability, validity, acceptability, and clinical utility of the TEDI for evaluating infants' development in four domains: 1) social communication; 2) ASD symptoms; 3) verbal and nonverbal development; and 4) affect and self-regulation. We will leverage an existing NIH-supported cohort of well-characterized infants enriched for developmental risk (R01 MH121416, PI: Miller) who will be assessed in the laboratory at 6 or 9, 12, and 18 months. In the current proposal, we will enroll and assess 110 of these infants (41 at familial risk for ASD, 41 at risk for ADHD, and 28 low risk for both) using the TEDI within a week of the laboratory assessments. Establishing the TEDI as a reliable and valid tool for assessing infants at-risk via telehealth has the potential to significantly increase families' access to specialized evaluations and increase the capacity for early identification of infants in need of services. It will also lay the groundwork for future efforts to conduct screening and intervention trials and may ultimately help to increase access to high-quality interventions and improve the developmental outcomes of many more underserved children with...