This study is a one year case study of a programme promoting physical activity and healthy eating habits in a secondary school. The aim was to describe and evaluate a school-based health promoting programme on interest in and participation in physical education (PE), eating habits and physical exercise habits, Sociocultural Attitudes Towards Appearance and self-efficacy for boys and girls before and after the programme. One hundred and sixty-four participants completed questionnaires in December 2007 and December 2008. The results showed increased interest and active participation in PE in girls and an opposite among boys at the post-test. Fewer boys reported regular eating habits after the programme. Girls scored higher on the Sociocultural Attitudes Towards Appearance Questionnaire subdomain awareness of a slimness ideal, and boys on the subdomain awareness of a muscular body as well as on the subdomain muscular appearance at the post-test. The results from this study cannot be generalized. Instead, the findings can be used for future research and to develop school-based health promotion programs. Conclusions and implications are discussed in the article.