Purpose: Easy access to fast-food restaurants in the immediate environment of a high school is such that a high proportion of students do not remain in school for lunch. Hence, the probability that they will eat a healthy meal is reduced. The aim of this study is to identify the behavioral determinants of "staying in school to eat lunch" among high school students. Design/methodology/approach: The Theory of Planned Behavior has been applied to the development of a questionnaire self-administered among 153 randomly selected high school students. Findings: Overall, 52.3 percent of students remained to eat at school every day during a follow-up period of two weeks. Logistic regression analyses showed that intention (OR: 16.22; 95 percent CI 7.08-37.21) was the sole predictor of behavior and that intention was determined by the descriptive norm (OR: 12.67; 95 percent CI 3.39-47.27), perceived behavioral control (OR: 11.46; 95 percent CI 4.53-29.04) and attitude (OR: 2.70; 95 percent CI 1.06-6.85). Practical implications: These findings suggest that a combination of interventions targeting both various individual determinants and environmental factors increases the likelihood that youngsters will remain at school to eat their lunch. Originality/value: To the best of one's knowledge, this is the first study applying the Theory of Planned Behavior to understand why high school students do not stay in school to eat lunch. This information should be very useful to those interested in developing interventions to promote the policy that students should stay in school to eat their lunch instead of going out to fast food restaurants in the nearby environment. (Contains 4 tables and 2 figures.)