The COVID-19 pandemic brought unprecedented challenges to the lives of families and children, affecting children’s adjustment. We examined the impact COVID-19 had on families and how child-rearing disagreements might be linked to child adjustment. Furthermore, given the role that children play in evoking parent responses within the family context, we also investigated how children’s temperament trait of anger/frustration might moderate the indirect pathway through child-rearing disagreements. We recruited 516 parents with a child between the ages 3 and 7 to complete an online survey measuring their perceived COVID-19 impact, and family and child functioning. Results indicate that greater COVID-19 impact, and child temperamental anger/frustration were each linked to greater child-rearing disagreements, and thereby, greater child stress. In addition, families reporting the most COVID-19 impact and having a child with high anger/frustration experienced the most child-rearing disagreements, and thereby, greater child anxiety during the pandemic. This work highlights how the COVID pandemic might have disrupted family processes, which in turn had negative consequences on the family, and suggest that less coparenting conflict might be a protective factor on the effect of the pandemic on child outcomes.