Aim To discuss the creation of a substantive theory using grounded theory. This article provides an example of generating theory from a study of mental health promotion at a high school in Finland.

Background Grounded theory is a method for creating explanatory theory. It is a valuable tool for health professionals when studying phenomena that affect patients’ health, offering a deeper understanding of nursing methods and knowledge.

Data sources Interviews with school employees, students and parents, and verbal responses to the ‘school wellbeing profile survey’, as well as working group memos related to the development activities. Participating children were aged between 12 and 15.

Review methods The analysis was conducted by applying the grounded theory method and involved open coding of the material, constant comparison, axial coding and selective coding after identifying the core category.

Discussion and conclusions The analysis produced concepts about mental health promotion in school and assumptions about relationships. Grounded theory proved to be an effective means of eliciting people’s viewpoints on mental health promotion. The personal views of different parties make it easier to identify an action applicable to practice.