This COBRE will establish a Center on Sleep and Circadian Rhythms in Child and Adolescent Mental Health at the EP Bradley Hospital in Rhode Island. Bradley Hospital is unique in the US as a psychiatric institution exclusively focused on children and a national resource for research in child and adolescent psychiatry. Links between mental illness and sleep are indisputable; probing and identifying the links from sleep and circadian rhythms to pediatric mental illness and mental health can identify important pathways to prevention and early intervention, not the least because these factors are amenable to behavioral change and to defined therapeutic targeting. This COBRE aims to build a bridge from the sleep and circadian knowledge base and relevant research methods to the outstanding mental health research and clinical care that characterize Bradley Hospital. The proposed COBRE Center would be the first and only NIH-funded research center to have an explicit focus on sleep, circadian rhythms, and pediatric mental health. The Center will train, mentor, and support junior investigators toward independent research careers. The Center’s research Cores will host training in the assessment of pediatric mental health and in sleep and circadian theory, science, and methods. The objective of this COBRE Center is to establish and build a comprehensive and sustainable resource to support the growth of research in pediatric sleep, circadian rhythms, and mental health while providing mentorship of junior Project Leaders for research and for transitioning to independent scientific careers with external funding. The Center is committed to diversity in faculty, mentors, investigators, research approaches and methods, and research participants. Four promising young investigators have each proposed a project that highlights the diverse and complex nature of this endeavor. Project 1 will measure sleep, circadian timing, and fMRI to assess Self Critical Rumination and Self Reassurance in adolescents at risk for suicidal thoughts and actions. Project 2 evaluates sleep patterns and circadian timing in youth who have a rare DNA copy number variant associated with autism and schizophrenia and includes a circadian clock gene. Project 3 assess in school children (grades 1-3) how green space use impacts sleep and mental health. Project 4 uses an intensive sleep and chronobiology in-lab approach to determine how sleepiness and memory in early adolescents with attention deficit hyperactivity disorder (ADHD) are affected by sleep bioregulatory factors. The ultimate goal of this COBRE is to ease the burden of these issues for children, adolescents, and their families through enhancing the research workforce and capabilities. The promise of this COBRE to fulfill its place as a true center of biomedical research excellence is strong, and the most important, special, and notable aspect of this proposed center is the vulnerable population that forms the heart of our work. This COBRE will establish a Center on Sleep and Circadian Rhythms in Child and Adolescent Mental Health at the EP Bradley Hospital with the objective to establish and build a comprehensive and sustainable resource to support the growth of pediatric sleep, circadian rhythms, and mental health research while providing mentorship of junior Project Leaders for research and for transitioning to independent scientific careers with external funding. The proposed COBRE Center will be the first and only NIH-funded research center in the country to have an explicit focus on sleep, circadian rhythms, and pediatric mental health. Extending the reach and accelerating the growth of a cadre of clinical scientists with multidisciplinary training and with the infrastructure to support advancement to independent research careers shows great promise to improve the health and well-being of children and adolescents and their families.