This study considered the effect of Triple P as a behavioural family intervention on mothers of children with separation anxiety disorder. Three hundred families with separation anxious children participated in this research which divided into intervention and control groups. The measuring tools were Parenting Scale, Depression Anxiety Stress Scale-42, Parental Bonding Instrument, Child Behavior Checklist and Client Satisfaction Questionnaire. The results showed that mothers in the intervention condition reported more improvements in parenting style and mother-child relationship than those in the control condition. Women were trained in the Triple P group also reported significantly lower rates of maternal depression, anxiety, stress and child misbehaviours than those in the control group. Iranian mothers reported high satisfaction with this intervention. In conclusion, positive parenting programme is an effective intervention in several aspects for mothers of children with separation anxiety disorder and their children.