There is very well-established evidence showing that over time and across early and middle childhood, there are bidirectional child and parent effects that link growth in child externalizing behaviors, EXT (i.e., aggressive and nonaggressive conduct problems) and harsh parenting, HP (i.e., verbally or physically reactive, intrusive and punitive behaviors directed at the child). In addition, these bidirectional patterns between parents and child operate within a broader individual and household context that impacts parents’ parenting discipline and child socio-emotional development. However, little is known about the role of child and household regulation factors that may strengthen or weaken negative bidirectional relations between HP and child EXT. Therefore, my dissertation mainly focuses on two important, modifiable, but understudied factors that would impact the link between HP and child EXT; the dissertation first focuses on child self-regulation abilities, which may help or hinder their ability to manage their frustration and anger in the face of difficult situations; the second critical component is household dysregulation – household chaos (i.e., crowded, noisy, lack of routines), which may tax parents’ and children’s capacities for regulating their behaviors and emotions in challenging situations. The overarching goal of my dissertation is to understand the bidirectional relations between HP and child EXT from middle childhood to early adolescence. In particular, my dissertation seeks to examine the role of child and household regulation on the bidirectional relations between HP and child EXT from age 6 to age 13. The central hypotheses of this dissertation are that there will be a longitudinal pattern of bidirectional relations between HP and child EXT, and that there will be a stronger bidirectional link among children and households with poorer regulation and a weaker bidirectional link among individuals and households with better regulation.