The purpose of the current study was to examine power assertive parental discipline and child difficult temperament as predictors of children's behaviour problems (internalizing, externalizing, and total behaviour problems) as well as mediating role of difficult temperament between power assertive parental discipline and children's behaviour problems. Participants were 118 children (53 boys) and their parents for the current study. Children's age ranged from 16 months to 36 months (M = 27.91, SD = 5.67). Mothers reported on their power assertive parental discipline, child temperament, and behaviour problems of children. Results from regression analysis showed that: (1) there was a positive association between parents' power assertive discipline and child behaviour problems. (2) Child difficult temperament was positively associated with children's internalizing, externalizing and total behaviour problems. (3) Children's difficult temperament mediated the association between power assertive discipline and child behaviour problems. Limitations and future directions of the current study are discussed.