There is very well-established evidence showing that over time and across early and middle childhood, there are bidirectional or reciprocal child and parent effects that link growth in child externalizing behaviors (i.e., aggressive and nonaggressive conduct problems) and harsh parenting (i.e., verbally and/or physically reactive, intrusive and punitive behaviors directed at the child). Furthermore, there is preliminary evidence that the child’s and parents’ capacities for self-regulation of emotions, cognitions, behaviors and physiology, and household regulation (i.e., routines, predictability) may moderate some aspects of these processes. However, there are major gaps in the literature regarding individual and household regulation moderation of bidirectional child and parent effects. The current study will address these gaps by examining task-based (i.e., executive function), surveyed and observed (i.e., effortful control), and physiological (i.e., resting cardiac respiratory sinus arrhythmia) measures of individual and household regulation on the bidirectional links between child externalizing and harsh parenting from 6- to 13-years. The findings will inform future research that will improve the efficacy of established and new interventions for family functioning. Also, by understanding this family mechanism, practitioners can incorporate this new information into their more holistic understanding of the family relationship and parents’ and children’s behavioral functioning.