This study examined the relationship between foster mothers' parenting stress and coparenting relationship quality, and the moderating influence of foster caregiver role support. The additional challenges faced by foster carers (e.g. caring for a traumatised child, financial strain) can increase their parenting stress, possibly leading to struggles with parenting and other relationships in the home, such as the coparenting relationship. However, having formal and informal support systems in place as a buffer for parenting stress have been found to be associated with positive foster caregiving experiences. The results of the study showed that helpful support from both formal and informal support systems may act as a buffer by mitigating the harmful effects of parenting stress on the coparenting relationship. The implications of these findings for services in promoting foster caregiver support, well-being, and placement stability are discussed.