PROJECT SUMMARY/ABSTRACT The overarching goal of this ECHO COVID-19 Administrative Supplement (NOT-OD-20-107) is to examine changes in children’s obesity-related behaviors that are occurring in tandem with societal changes related to the COVID-19 pandemic. Prolonged home stays, physical distancing precautions, school closures and economic disruption may impact children’s dietary intake, physical activity, screen time and sleep. This is a critical gap to fill because obesity prevention and treatment interventions over the next several years will need to be tailored to address the COVID-19-specific causes of obesity. Societal changes may differentially impact children from different socioeconomic and racial/ethnic groups and, in turn, exacerbate existing disparities in obesity. Further, variation in the degree of protective measures varies by US state, which may contribute to geographic variation in the effects of the pandemic on child health. Natural experiments are needed to assess the effects of the pandemic on obesity-related behaviors in a socioeconomically, ethnically and geographically diverse sample of children using rigorous measures of diet, activity, screen time and sleep. Kaiser Permanente Northern California (KPNC) is 1 of 4 awardees in the ECHO consortium proposing to collaborate on this Administrative Supplement. We propose a quasi-experimental pretest-posttest design among mother- child dyads from the 4 ECHO sites cohorts (n=375 dyads), including KPNC which consists of two pre-birth cohorts currently following offspring in early childhood. For the pretest, we will leverage existing data on diet, activity, screen time and sleep collected from dyads who completed their ECHO visit before March 2020. For the posttest, we will collect novel repeated measures data in Fall 2020 and Spring 2021 from the same dyads using remote data collection. We will address the following specific aims: AIM 1: to compare diet, activity, screen time and sleep prior to versus during the pandemic, with a focus on identifying children at high risk for adverse changes. We will explore whether the changes in obesity-related behaviors are modified by socioeconomic status, race/ethnicity and site location: AIM 2: using a mixed method approach (qualitative and quantitative), examine families’ daily routines during the pandemic, and parent perceptions of how societal changes influence children’s obesity-related behaviors. The ECHO COVID-questionnaire will quantitatively examine parent perceptions of how societal changes influence obesity-related behaviors. Qualitative interviews with parents will identify COVID-specific barriers to achieving healthy behaviors, reduced access to physical spaces that promote active play, and parents’ reliance on screen time as a replacement for in-person daycare. This study will be significant for ECHO and the broader child health community because lifestyle behavior changes during the pandemic may alter obesity risk and amplify exist...