This study aimed to explore the sources of parenting stress and the mental health of parents with kindergarten and primary school children in Hong Kong. It also examined the intervening effects of parenting self-efficacy on mental health of parents. Results indicated that parents who perceived their children as more demanding, less acceptable and less reinforcing had more parenting stress. Those who found their parental roles to be more restrictive also had more parenting stress. Lastly, parenting self-efficacy moderated the effects of parenting stress on the mental health of parents. Cultural and social factors were put forward to explain these findings and suggestions were made towards reducing the parenting stress experienced by parents with younger children in Hong Kong.