The effectiveness of the Parenting Program Stepping Stones/Triple P’ for children diagnosed with autism spectrum disorder (ASD) was evaluated. The parents of 13 children (nine boys, four girls), aged between four and twelve years (M = 6.7, SD = 2.16) took part in the study. Training sessions took place over 14 weeks and comprised eight meetings of two hours each. Parents’ ratings (pre- and post treatment, as well as six months after treatment) referred to children’s co-morbid symptoms as well as to parenting style. Additionally, parents rated pre- and post treatment autistic symptoms and parental stress. A few parents were included as a waiting list control group. The Parent Program reduced children’s co-morbid symptoms (d = .65) and improved parenting style (d = .97). Parental stress and core symptoms of ASD did not change. All in all, the Stepping Stones/Triple P can be seen as a valuable additional intervention in the treatment of children with an ASD.