The S4HM intervention will be evaluated using a cluster randomized controlled trial in eight secondary schools (=322 students) in New South Wales, Australia. The 6-month multi-component intervention will encourage adolescents to manage their recreational screen time using a range of evidence-based strategies. The intervention is grounded in Self-Determination Theory (SDT) and includes the following components: an interactive seminar for students, eHealth messaging, behavioral contract and parental newsletters. All outcomes will be assessed at baseline and at 6-months (i.e., immediate post-test).