There is increasing emphasis on wellbeing as a target for mental health promotion, especially during the formative period of childhood. Despite growing research on the importance of mental wellbeing, there is little information on how to effectively promote it or how to promote it equitably. This article presents a scoping review of interventions which seek to promote mental wellbeing and reduce inequities in children and young people living in high income countries. We used Fair Foundations: The VicHealth framework for health equity (VicHealth (2013) Melbourne, Australia: The Victorian Health Promotion Foundation) to identify points of entry at three layers of influence: (i) socioeconomic, cultural and political contexts, (ii) daily living conditions, and (iii) individual and family health-related factors. We identified more than 1000 interventions which aimed to prevent or treat childhood mental illness, but there were far fewer that aimed to promote children's or young people's mental wellbeing. The interventions we studied were either universal or specifically targeted children from disadvantaged families: none explicitly used an equity framework to guide their design or evaluation or addressed social gradients in wellbeing. Most interventions remained focused on proximate factors, although we also identified a handful of interventions that sought to address children's access to services and their educational and neighbourhood environments. However, we found encouraging evidence that interventions in family and educational settings were successful in building children's strengths and supporting positive parenting, universally and within disadvantaged groups. Such positive programme evaluations signal the potential for using a proportionate universalism approach that emphasizes equity in the promotion of mental wellbeing.