Technology and digital media (TDM), which includes TV viewing, playing computer games, and mobile device use, is common among preschool aged children. Many young children exceed the recommended ≤1 hour/day of parent supervised TDM use and this varies by sex and race/ethnicity. This is concerning because excessive TDM use has been linked less desired developmental and health problems. Some of these outcomes, such as sleep, weight status and executive functioning may be interrelated and should be examined together in one research program. However, past studies of TDM use among young children primarily relied on parent report of children’s typical use of TDM, resulting in both over- and under-reporting of TDM use. The validity of findings from these past studies are therefore questioned. FLASH-TV is a new technology developed by our team to passively, objectively measure children’s viewing of large digital screens, such as TVs or video-game consoles. In this research program we propose to leverage FLASH-TV along with new approaches for measuring children’s use of mobile devices, to robustly assess children’s use of TDM across multiple platforms (TV, mobile devices, and videogame consoles). This will allow us to investigate the role TDM use has on 1) health outcomes (sleep and child weight status) in project 1; 2) development (executive function) and weight status in project 2, while identifying any protective role parental scaffolding has on child TDM use, and 3) the effect of timing of TDM use close to bedtime on child sleep, circadian rhythm, and executive function using experimental studies in project 3. Three cores will be developed to provide synergy across projects and allow for a cost effective approach to achieve the aims of all projects. An Administrative Core will oversee the communication and coordination across projects. A Digital Assessment Core will oversee the passive and objective assessment of TDM use and sleep among children across all three projects. The Biostatistics and Database Management Core will develop and oversee databases, harmonize variables, and provide statistical support for all three projects. A cohort of 4-year old children (n=200) and their parent will be established for the overall program by project 1 to assess the child’s TDM use, weight status, sleep, and home environment. The cohort will have data collected over 10 days at two time-points, 12 months apart. Project 2 will leverage the same cohort and measure the child’s executive function and parent-child interactions during TDM use using robust approaches in an observation lab across three time points (baseline, 6 months and 12 months). A unique sample will be recruited to participate in the experimental studies for project 3. For the first time, these novel approaches to passively and objectively measure children’s TDM use in their home environment over multiple days allows us to assess the with-in and between child association of children’s TDM use on child ...