Introduction: Evidence worldwide suggests that the built environment must be reshaped to improve and sustain engagement in physical activity across communities to secure associated health benefits.Our Voice, an evidence-based community participatory approach, was used to directly engage school staff and students as "citizen scientists" in assessing their physical activity and food environments.Methods: Through the Our Voice process of Discovery, Discussion, Activation and Change, citizen scientists analyse their own data, create realistic action plans, and engage with local stakeholders to advance activity-supportive changes in their educational environments.To enable useful, standardized data collection, citizen scientists used a simple GPS-enabled mobile app capable of collecting geocoded visual and auditory data about walking routes and relevant environmental features. Results:The Our Voice framework is being utilised in educational settings in four international regions: Bogotá Colombia, Auckland, New Zealand, Cape Town, South Africa, and Irvine and Santa Clara County, CA, USA.Each citizen scientist used the mobile app to identify environmental features that hindered or facilitated physical activity and food environments, or that influenced choice of stairs versus elevators.In group discussions, citizen scientists reviewed their collected data, prioritized issues, and generated practical solutions with relevant stakeholders.Major qualitative and quantitative data from each project will be presented. Conclusion:These Our Voice projects have been successful in generating direct student, parent, staff, and stakeholder engagement in developing realistic environmental and policy solutions in differing school contexts and populations.