Public health disruptions have disproportionate consequences on low-income communities through pathways that likely exacerbate health disparities associated with poverty over extended periods. Young children are vulnerable to deleterious effects of public health disruptions on psychosocial development but have received less attention and resources. Preventive interventions focused on relational health (e.g., positive and structuring parenting practices, parent-child relationship quality) have been shown to address the consequences of poverty for young children. However, such interventions have yet to be tested during public health disruptions, including in the context of compounding effects of poverty. The current application provides a unique opportunity to determine whether healthcare- and community-based interventions initially targeting families with young children living in poverty can prevent widening of health disparities. We propose to examine these critical issues by pooling and harmonizing seven data sets across four studies (including three NICHD R01 awards) in: 1) three very different cities (New York, NY; City, Pittsburgh, PA; and Flint, MI); 2) that include low-income families; 3) involve trials of scalable preventive relational health interventions delivered in early childhood (primarily birth to 3 years), the majority with a randomized design; and 4) assess families longitudinally with multiple informants/methods to assess family socioeconomic risk, parent-child relational health, and child psychosocial development in the context of public health disruptions, through at least the preschool period. Thus, the current application examines the consequences of public health disruptions for families’ relational health and child psychosocial development, the potential protective role of relational health interventions in attenuating consequences of public health disruptions, and the variation in these effects across intervention timing and level of exposure to public health disruptions, as well as the potential moderating influence of pre-existing family-related risk. Findings will address complex drivers of health disparities and our ability to utilize population-scalable, preventive parenting interventions to promote children’s healthy psychosocial development in the context of public health disruptions, with implications across the life course. In addition to determining the degree to which preventive interventions buffer consequences on parents and children, the questions that can be addressed by combining and harmonizing across these rich data sets promise to offer the field critical information about family health and well-being.