Objective: To analyse the interrelated processes of identity, participation and knowledge in the context of the health educational Lifecalculator computer game. The analysis focuses on if and how this school-based health promotion initiative communicated relevant health knowledge to adolescents. Further development of the concept of health identity was a secondary objective of the study.

Setting: Danish public schools.

Methods: A qualitative study based on 21 focus group interviews with a total of 103 adolescents and 10 individual interviews with their teachers.

Results: The simplified description of health and health choices in Lifecalculator makes it hard for the adolescents to relate the game to their everyday lives. They know that everyday health choices are more complex and they consequently dismiss the information altogether and do not gain much knowledge. The adolescents’ identities and the way they interpret themselves and their health in relation to others decide if and how they acquire knowledge. Healthy adolescents, who consider themselves as healthy, find it easier to relate to the health knowledge than the unhealthy adolescents who are aware of their unhealthiness. Lifecalculator seems to confirm that healthy adolescents (who view themselves as healthy) are healthy and unhealthy adolescents (who view themselves as unhealthy) are unhealthy and, as such, this approach does very little in terms of motivating participation and presenting the adolescents with new health knowledge.

Conclusions: The study of Lifecalculator and the theoretical advances disclose the multi-layered interrelatedness of health identity, knowledge and participation. This interrelatedness creates multiple perspectives for both practice and research.