PROJECT SUMMARY/ABSTRACT About a fifth of U.S. children are obese. Pediatric obesity has significant long-term ramifications for adult health. Despite federal initiatives targeting physical activity and nutrition, rates of pediatric obesity have not significantly decreased in the last two decades. This warrants increased attention to factors instantiating risk for later obesity. Few studies examining stress biology and child obesity utilize longitudinal designs, objective measures of stress, or integrate across multiple biological systems despite increasing acknowledgement of their complicated interplay. The current proposal seeks to address gaps in the literature by integrating several biological and developmental systems during early childhood into a predictive model for later overweight/ obesity. Biological systems of interest include the Sympathetic Adrenal-Medullary (SAM) System, which quickly triggers physiologic and behavioral reactions to stressors, and Hypothalamic-Pituitary-Adrenal (HPA) Axis, a hormonal response system reacting to longer-term stressors. This study utilizes collected data (RC1DK086376 PI: Lumeng/Miller) to examine: (1) pathways between SAM system and HPA Axis functioning during a standardized stress task in toddlers and body-mass index (BMI) in middle childhood, (2) bi-directional longitudinal associations between behavioral sleep quality and BMI across preschool to middle childhood, and (3) the moderating role of behavioral sleep quality in longitudinal relationships between SAM system and HPA axis stress reactivity in preschool and BMI in middle childhood. Children provided saliva samples throughout a standardized stress task, from which cortisol (primary output of the HPA axis) and alpha amylase (indicating SAM system activity) were assayed. Results will elucidate early biological embedding of risk for overweight/ obesity and can inform concurrent type and timing of effective interventions. An extensive training plan has been designed alongside the current study to equip the applicant with skills needed for an independent research career as a clinical scientist. Fellowship training goals are to: (1) Refine distinct research interests and position for a clinical scientist career leading to an impactful research program, (2) Learn skills needed to independently run a lab, (3) Hone skills in statistical modeling suited for longitudinal, multi-dimensional data representing several biological systems, (4) Build productive, bi-directional community partnerships and skills in disseminating research, and (5) Develop grant-writing skills. The applicant has assembled a dedicated, inter- disciplinary team of scientists with relevant expertise in sleep, stress biology, obesogenic pathways, family contextual factors, and community-academic partnerships. Training activities will primarily occur in the Depart- ment of Psychology, University of Denver, where faculty conduct interdisciplinary, developmental psycho- biology research u...