SUMMARY Poverty and racism are linked to disparities in early child development (ECD), including school readiness (pre- academic skills, self-regulation, social-emotional well-being), which are a core contributor to long-term health and mental health outcomes. These disparities begin early in life, widen as children age, and persist across the lifespan. Poverty and racism also increase the likelihood of adverse childhood experiences (ACEs) and decrease the likelihood of positive childhood experiences (PCEs). Importantly, PCEs are not simply the absence of ACEs; they are factors that are beneficial for children’s development and may be especially important in providing a buffer for the impacts of ACEs. Two interrelated frameworks (Stress and Investment) illustrate how ACEs and PCEs impact ECD through a key common pathway of early relational health (ERH; parent-child relationship quality, structuring the home environment, responsivity/cognitive stimulation). Thus, enhancing ERH by both addressing ACEs and promoting PCEs is critical for mitigating disparities in ECD. Evidence-based preventive interventions (EBPIs) designed to reduce these disparities have increasingly been located in pediatric primary care due to its population-level reach, frequent visits, trusted relationships, and potential for low cost. However, few EBPIs have successfully integrated strategies to concurrently and directly address ACEs and promote PCEs, limiting their capacity to fully address disparities synergistically, particularly for families with fewer resources. Moreover, knowledge gaps related to dissemination and implementation (D&I) of integrated EBPIs represent a key barrier to improving implementation effectiveness and impact. We propose a novel integration of HealthySteps (HS) and Video Interaction Project (VIP), two exemplar, American Academy of Pediatrics (AAP)-recommended EBPIs. HS provides a stepped-care approach with universal screening for ACEs and additional support and referrals for families with increased concerns. HS has been shown to reduce family vulnerabilities and negative relationship quality elements of ERH. However, HS has limited impact on PCEs, suggesting additional strategies may be needed to improve effectiveness of the HS stepped-care approach in enhancing ERH. Integrating VIP may address this gap with its focus on video- recording parents and children interacting with a toy or book provided by the program and real-time, strengths- based feedback. VIP has impacts on parenting assets and responsivity/cognitive stimulation elements of ERH. We will test an integrated HS+VIP model in order to: 1) identify best practice strategies for implementing integrated EBPIs in diverse pediatric care sites; 2) examine effectiveness and implementation outcomes of the HS+VIP model; and 3) examine health disparities mechanisms underlying these outcomes. This integrated model has the potential for population-level reductions in disparities in ECD outcomes by targe...