This study examined the mediating role of parenting on the relation between parental personality and toddlers' externalising behaviours. Participants were 112 boys and their parents. The data were analysed using multilevel modelling and moderated mediation analyses. Several associations were found between parental personality and parenting dimensions. Additionally, several parenting dimensions were associated with children's externalising behaviours. Emotional stability was the only parental personality trait that was related to children's externalising behaviours. The effect of maternal emotional stability on children's aggressive behaviours appeared to be mediated by maternal support. For fathers, there appeared to be a direct effect of emotional stability on children's aggressive behaviours. In addition, for both mothers and fathers, emotional stability was directly related to children's attention problems. Copyright © 2007 John Wiley & Sons, Ltd.