The aim was to examine middle school-aged pupils’ participation in an action-oriented school health promotion project and investigate its effects on their health experience, learning and influence. A survey was sent eight times to middle school-aged pupils (n = 105). A descriptive analysis with group comparisons was followed by a regression analysis. Health differences were found between gender and age. Aspects of pupil influence and learning about health showed positive progression during the project. Satisfaction with school performance was most associated with health experience. Thus, health experience, gender, and age are factors to consider when planning similar health promotion projects in schools.