Objective: We evaluated an intervention to increase positive parenting, reduce corporal punishment, and improve children's mental health community-wide. All Parenting for Lifelong Health programmes were available to all interested parents alongside an action media intervention designed to amplify positive parenting messages across the community. Method: Three community-wide surveys of parents and of children aged 10+ were conducted at baseline and at 18-month intervals. Parent and child surveys assessed parenting and corporal punishment; parent surveys also addressed intimate partner violence (IPV), parent and child mental health, parent alcohol misuse, and parenting stress. Results: 536 parent-child dyads were included in the surveys; 110 (20.5%) parents attended a parenting programme at least once. Positive parenting did not increase across the whole community; there was a trend towards reduction of corporal punishment. Parenting stress declined and children's mental health improved by the third survey, possibly through increased parent employment rather than the intervention. IPV, parent mental health, and parent alcohol misuse were unchanged, and were associated with less positive parenting and more children's mental health symptoms. The action media process may indeed have enabled diffusion of parenting information, but also appeared to be associated with small negative effects on positive parenting, parenting stress and children's internalising and externalising. Conclusions: Reduction in parenting stress, a trend towards a reduction in corporal punishment, and improvement in children's mental health, were observed by year three. Parents' mental health, substance abuse and IPV must be addressed alongside parenting interventions to improve both parenting and children's mental health.