PROJECT ABSTRACT Research shows that a stable diagnosis of autism spectrum disorder (ASD) can be made by trained professionals at 18-24 months2,3 and yet the median age of diagnosis in the US is 4-5 years of age5. Lower income, minority, and rural families receive a diagnosis up to 1.5 years later6,7 and more likely miss the window of opportunity for early intervention (EI). One of the greatest challenges we face, in spite of scientific advances and investments, is how to bridge the healthcare science-to-service gap and address health disparities in access to evidence-based EI for children with ASD. Doing this would be the best solution to improve lifelong outcomes, reduce costs to society, and change the landscape of autism. In response to RFA-MH-17-008, the Autism ACTION Network?a new interdisciplinary network of 8 institutions?will blend clinical effectiveness and implementation research designs to study individual and combined effects of 2 evidence-based interventions in real world settings: 1) engage families to access resources and support when they first learn their child has signs of ASD using an evidence-based intervention8 that integrates motivational interviewing and problem- solving education (MI+PSE); and 2) coach families to embed evidence-based intervention strategies for toddlers with ASD in everyday activities using the Early Social Interaction (ESI) model9. Building on existing infrastructure, we will infuse mobile technology using the Autism Navigator collection of web-based courses and tools. Families will be recruited by screening in community-based primary care and EI systems in 3 diverse regions in 2 states: Florida and Massachusetts. In Phase 1, we will compare the effectiveness of adaptive interventions that use MI+PSE with and without ESI in a 2-stage Sequential Multiple Assignment Randomized Trial (SMART) design on family engagement in EI, parent use of intervention strategies in everyday activities, and child outcomes of social communication, active engagement, autism symptoms, developmental level, and adaptive behavior. In Phase 2, we will construct an adaptive intervention to optimize the effects of MI+PSE with ESI based on the SMART and study the feasibility of implementation in two new service systems in California--Kaiser Permanente Healthcare System and the National Black Church Initiative. This network brings a unique interdisciplinary team with expertise spanning early detection, maternal mental health, clinical trials, health disparities, implementation science, and policy. Our dynamic technology platform has ambitious dissemination aims of informing a community of change agents committed to impact at the population level. This research network can build the capacity of community-based systems to provide earlier and widespread access to cost-efficient, community-viable treatment and be ready for immediate and rapid implementation across the US. Findings will advance science by providing researchers with a method for rapidly deploying evidence-based practices, enabling research at younger ages?accelerating genetic, neuroscience, and intervention research?and lead to transformative changes in workforce development and healthcare delivery.