Background: The promotion of physical activity and health has become a universal challenge. The Sotkamo Physical Activity as Civil Skill Program was implemented to increase students' physical activity by promoting supportive psychological and physical school environment. The aim of this study was to evaluate the effectiveness of the school-initiated physical activity program on secondary school students' self-reported physical activity. Methods: The sample included 847 students (experimental condition school?=?208, control school?=?639) at the age of 12 to 14?years from northeast and central Finland. The program was conducted across 1 academic year and 2 measurement phases were carried out using self-report questionnaires in April 2011 and 2012. Results: The findings highlighted that the program appeared to be effective as an approach to change the sharp decline in the pattern of Grade 7 students' self-reported physical activity across 1 school year. Specifically, change in the experimental condition students' self-reported physical activity was 13.4% higher compared the students in the control condition. Conclusion: On the basis of current findings, increased opportunities for school day physical activities have the potential to affect large number of students and are an efficient strategy for promoting regular physical activity.