ABSTRACT Changing parent behavior is one of the most potent mechanisms to prevent and treat obesity among young children. However, many early childhood obesity prevention and treatment interventions that target parent behavior have been unsuccessful. Self-regulation, or one’s ability to control emotions, cognitions, and behavior, is a fundamental mechanism of action underlying behavior change, maintenance, and adherence. Motivated by this evidence, the parent grant, R01HL150848 (Maternal Self-Regulation and Early Childhood Obesity (aka, the SPROUT study)), aims to elucidate how mothers’ self-regulation supports or inhibits engagement in parenting behaviors that promote young children’s healthy weight. In response to NOT-OD-22-140, this supplement will allow for the addition of an assessment of mothers’ co-parents’ self-regulation to the SPROUT study. This new complementary data, along with the parent projects’ existing data, will be used in analyses to achieve the following specific aims: Aim 1. Characterize self-regulation among parenting dyads, Aim 2. Examine concurrent associations between parenting dyads’ self-regulation, mothers’ weight-related parenting behaviors, and families’ weight-related home environments, and Aim 3. Explore how parenting dyads’ self- regulation predicts changes in mothers’ weight-related parenting behaviors and families’ weight-related home environments over time. These aims will illuminate how self-regulation within parenting dyads, not just mothers’ self-regulation alone, facilitates or impedes mothers’ use of recommended weight- related parenting behaviors and development of health-promoting home environments. Understanding how self-regulation among parenting dyads may influence parent behavior and the home environment will provide novel, critical insight into the value and specificity of targeting self-regulation as a mechanism of action to improve early childhood obesity prevention and treatment intervention effectiveness. Further, by being one of the few studies to examine self-regulation within spousal/romantic partner/parenting dyads, versus only among individuals, the knowledge gained has transdiagnostic implications and contributes to OBSSR’s priority of facilitating cumulative, integrated, and synergistic behavioral and social sciences that can be optimized and translated across conditions.