PROJECT ABSTRACT Child maltreatment (CM) is a significant public health concern that affects one million children annually, exerts a societal cost of $2 trillion, and increases the risk for a range of adverse health outcomes. Difficulties in emotion regulation (ER) is one potential pathway explaining how CM leads to a range of sustained adverse health outcomes and empirical efforts to identify factors effecting ER, positively or negatively, have significant potential to inform intervention strategies for children exposed to maltreatment. The Caregiver-Child (C-C) relationship is critical to the development of ER abilities, but so far has not been thoroughly examined as a potential mediator of the CM-ER relation in the CM population. Furthermore, no CM studies have used observational methodology to examine dynamic, moment-to-moment C-C communication processes with older children and adolescents. Such innovation and methodological rigor will elucidate real-time, bidirectional processes during key developmental periods that can highlight specific targets for prevention and treatment with the CM population. Leveraging observational data collected from a large, multi-wave, prospective NIH- funded cohort study, The Child Health Study (P50HD089922), the present study will examine C-C communication dynamics over three interactions focusing on C-C relationship enhancing and problem-solving topics. The CHS affords richness in characterizations of CM via coding of official case files via the Maltreatment Classification System, multi-informant assessment of caregiver and child health and socio- emotional well-being, and an established C-C interactional paradigm. Caregiver validating and invalidating behaviors during C-C interactions will be coded as well as child positive and negative affect. Importantly, caregiver validating and invalidating behaviors have yet to be studied at more intensive time-scales (e.g., 30 second epochs) nor in direct relation to child positive and negative affect during C-C conversation, and thus the present study has the potential to make a significant, innovative contribution to the CM literature. This fellowship proposal will examine change and intra-individual variability in caregiver validating and invalidating behaviors (Aim 1a) and child positive and negative affect over the course of three C-C interactions (Aim 1b), as well as how caregiver validating and invalidating behaviors are longitudinally and bidirectionally related to child positive and negative affect (Aim 2a). Hypothesized caregiver and child trait characteristics will also be tested as moderators of these dyadic communication process (Aims 1c and 2b). Finally, C-C interaction dynamics will be tested as mediators in the longitudinal relation between CM and ER (Aim 3), elucidating novel behavioral targets for prevention and treatment in the CM population. Ultimately, successful prevention and treatment efforts will reduce the personal and lifelong public health bur...