It has been 17 years since the first interventions to reduce children’s sedentary behaviour were published. However, child and adolescent engagement in sedentary behaviour remains high. There have been more than 40 interventions to reduce children’s and adolescents’ screen time, but strategies to reduce or break up overall sitting throughout the day have been infrequently studied. Reducing sitting in the school setting via active breaks and an active curriculum, and environmental changes in the classroom (e.g. sit–stand desks) show promise. The home and transport settings have infrequently been targeted. Given the pervasiveness of sitting and reclining while at home during waking hours (for homework, hobbies, entertainment, and other purposes) and passive forms of transport such as car travel among children and youth, there is much scope to reduce sitting in these settings. Very few efficacious interventions have been translated into policy or practice. If these interventions are to have a sustained impact on child and adolescent populations, greater consideration of factors facilitating and/or hindering their incorporation into policy and practice is necessary. To successfully implement sedentary behaviour programmes and help children and adolescents meet sedentary behaviour public health recommendations, replication of successful interventions at scale is required. Ideally, cost-effective efficacious strategies need to be integrated into current systems and target not just the individual, but sociocultural norms and physical, organizational, and policy environments to effect lasting and wholesale changes in sedentary behaviour at a population level.