Childhood onset conduct problems present some of the most significant challenges to mental health and public services today. Parent management training is among the most effective treatments for conduct problems, and yet a significant proportion of families do not benefit from this approach. This may be because key elements of parenting, such as parental cognitions, are not directly addressed in such interventions. This study investigated the role of mothers' interpersonal schemas in the maintenance of conduct problems and their relationship to parenting behaviour. It examined whether mothers of 7 to 11-year-old boys with conduct problems would have more negative child-related interpersonal schemas (Hill and Safran, 1994), and related negative parenting behaviours, observed during two parent-child interaction tasks, than mothers in a comparison group. The findings showed that there was a significant difference between the two groups in both maternal Negativity and Warmth and child-related interpersonal schemas. However, no relationship was found between parenting behaviour and child-related interpersonal schemas. The results suggest that targeting maternal cognitions in addition to negativity and warmth may enhance interventions for childhood onset conduct problems. However, more research needs to be done to ascertain which kinds of cognitions relate most closely to parenting behaviour in stressful situations.