Improving parenting skills can improve a range of mental health outcomes in infancy, childhood, and adolescence, and can improve both physical and mental health in adulthood. High-quality, evidence-based parenting programmes are especially effective for reducing children’s antisocial behaviour and promoting attachment security. This form of early intervention confers lasting benefits well into adulthood, on intelligence and academic functioning, as well as a range of mental health outcomes, such as antisocial personality disorder, crime, drug addiction, and early death. The skill of the mental health practitioner has a substantial effect on outcomes, as well as choosing a high-quality parenting programmeme, it is important to train the practitioner well and subsequently to ensure there is ongoing supervision. To widen access, more online programmes need to be developed.