After successful pilot projects, Zhejiang Province, China, decided to systematically scale-up health promoting schools (HPS) over the entire province of 47 million. This study describes the interventions and self-reported changes in attitudes, knowledge and behavior during the first phase of scaling-up. Group interviews were conducted with a sample of 191 participants (school administrators, teachers, students and parents) from nine schools with a total of approximately 15 200 students. Grounded theory guided data analysis. Schools implemented all HPS components (school health policy, physical school environment, psychosocial school environment, health education, health services, nutrition services, counseling/mental health, physical exercise, health promotion for staff and outreach to families and communities), adapted to local circumstances. Participants reported a range of changes in attitudes (paying more attention to health, attaining better 'psychological quality' and confidence, forming friendships between teachers and students and feeling more relaxed), knowledge and concepts (increasing knowledge about various health issues, developing a broader concept of health and gaining better understanding about the HPS concept) and behavior (actively participating, increasing physical activity, improving sanitary habits, reducing or quitting smoking, eating more nutritiously, increasing safety behavior, sustaining less injuries and improving parent-child communication). This qualitative study shows the feasibility and efficacy of implementing HPS in Zhejiang Province, China.