Autism is a common neurodevelopmental condition that affects functioning and well-being in a myriad of domains across the life course. The proposed Autism Center of Excellence, “Public Health and Autism Science advancing Equitable Strategies across the life course” (PHASES) application proposes to employ an overarching public health research framework to examine health determinants, health inequity – especially in under-represented diverse populations – and health services delivery and their impact on health outcomes. Projects in our center highlight different stages of the life course – early childhood, adolescence to young adulthood, and older adults. Project 1 addresses predictors of age of diagnosis among young children with autism, with emphasis on inequities in access to universal, high-fidelity screening during primary care visits. Projects 2 and 3 examine Medicaid claims and other national data to address key issues arising from the disproportionate burden of co-occurring health conditions in autistic adolescents and young adults (Project 2) and middle age-to-older adults (Project 3). Project 4 develops a new tool to support transition from pediatric to adult healthcare in young adults on the spectrum, with emphasis on minimally verbal adults. Each of the four studies targets unique understudied groups characterized by potentially modifiable adverse outcomes: young children with delayed autism detection, autistic adolescents and young adults with co-occurring conditions, older autistic adults with co-occurring health and cognitive deterioration, and young autistic, minimally verbal adults at risk for poor health care transition. The three Center Aims address the following research goals at three different key life stages: Aim 1 investigates modifiable health determinants for autistic individuals; Aim 2 evaluates inequities in health and health services, especially in under-represented minorities and economically disadvantaged persons on the autism spectrum; and Aim 3 examines the relations between health services delivery and health outcomes. The Center will be supported by three cores facilitating synergy across projects: the Administrative Core streamlines communication and collaboration across projects; the Dissemination and Outreach Core facilitates engagement with diverse stakeholders and expands our existing activities to emphasize bidirectional communication between our team and the community; and the Data Core ensures quality, integrity, and security of data from large and diverse sources (e.g. Medicaid, Medicare, electronic health records). Overall, the Center will address preventable adverse outcomes and promote wellbeing in individuals on the autism spectrum, with a focus on several priorities identified by the Interagency Autism Coordinating Committee, including research across the lifespan, reducing inequities, and improving health outcomes for autistic persons.