Schools can have a significant role in affecting the mental health and wellbeing of both students and staff, with considerable implications for society as a whole. Hence, there is a need for school-based interventions to both assist those experiencing mental health problems and to implement activities and policies that facilitate the enhancement and maintenance of good mental health. Unlike most school mental health interventions that are focussed on, and specific to, the school setting, the Act–Belong–Commit Mentally Healthy Schools Framework is based on the principles of the Act–Belong–Commit community-wide general population mental health promotion campaign, which has been adapted to the school setting via the World Health Organisation’s Health Promoting Schools Framework. The Mentally Healthy Schools Framework is a whole-school approach to enhancing both student and staff mental health. This paper reports the findings of a preliminary impact survey administered to students after the adoption of the Framework in a number of primary and secondary schools in Western Australia. Students from two schools that had only recently adopted the Framework completed a “Baseline” questionnaire, and students from three schools that had been implementing the Framework for at least 17 months completed a “Follow-up” questionnaire. The results suggest that the Mentally Healthy Schools Framework, adapted from a community-wide campaign, can have a positive impact on students in terms of increasing openness about mental health, increasing awareness of behaviours conducive to good mental health, and increasing engagement in behaviours to improve their mental health. Such positive impacts have clear implications not only for prevention of mental disorders, but for academic achievement, employment, and overall contribution to society.