Many schools have recently adopted food policies and replaced unhealthy products by healthy foods. Consequently, adolescents are more likely to consume a healthy meal if they stay in school for lunch to eat a meal either prepared at home or purchased in school cafeterias. However, many continue to eat in nearby fast-food restaurants. The present paper describes the development of a theory-based intervention programme aimed at encouraging high school students to stay in school for lunch. Intervention Mapping and the Theory of Planned Behaviour served as theoretical frameworks to guide the development of a 12-week intervention programme of activities addressing intention, descriptive norm, perceived behavioural control and attitude. It was offered to students and their parents with several practical applications, such as structural environmental changes, and educational activities, such as audio and electronic messages, posters, cooking sessions, pamphlets, improvisation play theatre, quiz, and conferences. The programme considers theoretical and empirical data, taking into account specific beliefs and contexts of the target population. This paper should help programme planners in the development of appropriate interventions addressing the problem. (Contains 3 tables and 2 figures.)