Teachers and youth sports coaches are in prominent positions to support young people and their mental health. However, the way these professionals perceive their roles is likely to be a powerful influence on such behaviour. This article investigates and compares the effect of four types of role perceptions—role breadth, instrumentality, efficacy, and discretion—on teachers' and coaches' engagement in helping behaviour that supports young people's mental health through promotion, prevention, and early intervention. An online survey was completed by 117 teachers and 131 coaches. Results from three multiple group path analyses revealed role breadth, instrumentality, and efficacy significantly influenced teachers' and coaches' helping behaviour. The extent to which role perceptions predicted helping behaviour did not differ between teachers and coaches. Assisting teachers and coaches to carry out promotion, prevention, and early intervention behaviour increases young people's access to mental health support and may help to reduce the burden of mental health problems among Australian young people.