Background: Parenting and coparenting are both important for children’s adjustment, but their interaction has been little explored. Using a longitudinal design and considering two children per family, we investigated mothers’ and fathers’ perceptions of coparenting as moderators of associations between their coercive parenting and children’s disruptive behaviour. Methods: Mothers and fathers from 106 ‘intact’ families were included from the Twins, Family and Behaviour study (TFaB). At Time 1 (Mchild age=3 years 11 months, SDchild age=4.44 months) parents reported on their coercive parenting and children’s disruptive behaviour via questionnaire; at Time 2 (Mchild age=4 years 8 months, SDchild age=4.44 months) perceptions of coparenting and the marital relationship were collected by telephone interview. Questionnaire-based reports of children’s disruptive behaviour were collected at follow-up (Mchild age=5 years 11 months, SDchild age=5.52 months). Multilevel modelling was used to examine child-specific and family-wide effects. Results: Conservative multilevel models including both maternal and paternal perceptions demonstrated that maternal perceptions of coparenting and overall coercive parenting interacted in their prediction of parent-reported child disruptive behaviour. Specifically, accounting for perceived marital quality, behavioural stability, and fathers’ perceptions, only in the context of perceived higher quality coparenting was there a positive association between mother-reported overall coercive parenting and children’s disruptive behaviour at follow-up. Conclusions: When combined with highly coercive parenting, maternal perceptions of high quality coparenting may be detrimental for children’s adjustment.